Para comprobar el cálculo, mi profesora nos hizo sumar todos los gastos y restar el descuento.

Para + infinitive is a very common way to express purpose in Spanish. Here, para comprobar el cálculo means to check/verify the calculation or in order to check the calculation.

So the structure is:

para + infinitive = to / in order to

Examples:

• Para aprender, hay que practicar. = To learn, you have to practise.
• Para abrir la puerta, necesitas una llave. = To open the door, you need a key.

In this sentence, it explains why the teacher made them do the operation.

Here comprobar means to check, to verify, or to confirm.

It is not the same as probar in most contexts.

• comprobar = to check/verify
• probar = to try, to test, or to taste

Examples:

• Voy a comprobar el resultado. = I’m going to check the result.
• Voy a probar este pastel. = I’m going to try/taste this cake.

So in this sentence, comprobar el cálculo means checking whether the calculation is correct.

El cálculo means the calculation. It focuses on the mathematical calculation itself.

You might also hear:

• la cuenta = the sum / the arithmetic / the bill, depending on context
• la operación = the mathematical operation
• el resultado = the result

Here, el cálculo is a natural choice because the sentence is about checking the correctness of a calculation by adding and subtracting.

In Spanish, possessive adjectives usually go before the noun:

• mi profesora = my teacher
• tu libro = your book
• nuestro coche = our car

The longer form, such as la profesora mía, does exist, but it is less neutral and usually sounds more emphatic, contrastive, or stylistically marked.

So in normal everyday Spanish, mi profesora is the standard choice.

It means she made us add up or she had us add up.

This is the causative use of hacer:

hacer + indirect object + infinitive

Meaning:

• to make someone do something
• to have someone do something

So:

• mi profesora nos hizo sumar = my teacher made us add up

More examples:

• Me hizo esperar. = He/She made me wait.
• Nos hizo repetir el ejercicio. = He/She made us repeat the exercise.

This is a very common pattern in Spanish.

Because nos is the object pronoun, while nosotros is a subject pronoun.

Here the teacher is doing something to us: she made us do something.

So:

• nos = us
• nosotros = we

Compare:

• Nosotros sumamos los gastos. = We add up the expenses.
• La profesora nos hizo sumar los gastos. = The teacher made us add up the expenses.

In this sentence, nos is the correct form because it is not the subject of the sentence.

Hizo is the preterite of hacer, and it presents the action as a completed event.

• mi profesora nos hizo sumar... = my teacher made us add...
  This sounds like a specific action that happened.

If you used hacía, the imperfect, it would suggest a habitual or background action:

• Mi profesora nos hacía sumar todos los gastos... = My teacher used to make us add up all the expenses...

So hizo fits a single completed event, which is what this sentence suggests.

Both are possible, but they are different structures.

1. hacer + infinitive

   • Mi profesora nos hizo sumar todos los gastos.
   • Very common and direct.
   • Means My teacher made us add up all the expenses.

2. hacer que + subjunctive

   • Mi profesora hizo que sumáramos todos los gastos.
   • Also correct, but a bit heavier in structure.
   • Means roughly the same thing.

The version with hacer + infinitive is often the most natural choice when saying someone made another person perform an action.

Because todos los gastos is a thing, not a person.

In Spanish, the personal a is usually used before a specific human direct object:

• Veo a mi profesor. = I see my teacher.

But you do not use it with things:

• Veo el libro. = I see the book.
• sumar todos los gastos = add up all the expenses

So no a is needed here.

Because todos has to agree in number and gender with gastos.

• gasto is masculine singular
• gastos is masculine plural

So:

• todo el gasto = all the expense / the whole expense
• todos los gastos = all the expenses

Agreement is important:

• toda la clase
• todas las clases
• todo el dinero
• todos los gastos

Yes, there are a few possibilities, but they are not identical.

• sumar todos los gastos = add up all the expenses
  This is the clearest and most complete version.

• sumar los gastos = also possible; it can still mean add up the expenses

• sumarlos = add them up, if the expenses have already been mentioned

• sumar todos on its own is less natural here unless the context makes it very clear what all refers to

So the sentence uses the most explicit form.

Good question. On its own, restar el descuento means subtract the discount, but Spanish often leaves out information that is obvious from context.

So here the full idea is something like:

• restar el descuento del total
• restar el descuento a la suma final

But since the context is already about checking a calculation, restar el descuento is enough.

This kind of omission is normal when the missing element is easy to understand.

It can mean both, and in everyday English, add up is often the most natural translation.

• sumar = to add / to add up / to sum
• restar = to subtract

In a school or maths context:

• sumar todos los gastos = add up all the expenses
• restar el descuento = subtract the discount

So add up is usually the best natural translation here.

Yes, and it follows a very common Spanish pattern:

subject + object pronoun + hacer + infinitive + objects

Breakdown:

• mi profesora = subject
• nos = us
• hizo = made
• sumar = add up
• todos los gastos = all the expenses
• y restar el descuento = and subtract the discount

Spanish word order is somewhat flexible, but this order is very natural and clear.

For example, these are possible but less neutral:

• Mi profesora hizo que sumáramos todos los gastos...
• Nos hizo mi profesora sumar...
  This sounds marked and is not the normal choice here.

So the original order is the standard one.