Ochenta es más que setenta.

A natural Latin American pronunciation is:

• ochenta = oh-CHEN-tah
• es = ess
• más = mahs
• que = keh
• setenta = seh-TEN-tah

Put together:

oh-CHEN-tah ess mahs keh seh-TEN-tah

The stress falls on -chen- in ochenta and -ten- in setenta.

Es is the he/she/it is form of ser.

Here, Spanish is treating ochenta and setenta as the numbers themselves, so the sentence uses a singular linking verb:

• Ochenta es...
• not Ochenta son...

This is like English Eighty is..., not Eighty are...

Use más ... que when you are comparing one thing directly to another:

• Ochenta es más que setenta.

Use más de before a number or quantity meaning more than in the sense of over:

• más de setenta personas = more than seventy people

So:

• comparing 80 to 70 → más que
• talking about an amount over 70 → más de

Yes. In fact, mayor que is very common in math and sounds more precise for numbers.

So these are both possible:

• Ochenta es más que setenta.
• Ochenta es mayor que setenta.

A useful rule:

• más que = general more than
• mayor que = especially common for numerical comparison, like greater than

In math class, the symbol > is usually read as mayor que.

The accent mark is important. Más with an accent means more.

Without the accent, mas is a different word meaning but, and it sounds literary or old-fashioned in most modern Spanish.

So here it should be:

• más = correct

Because que here is part of the comparison structure más ... que.

• que = no accent, used in comparisons and many other grammar structures
• qué = with an accent, used in questions or exclamations

For example:

• Ochenta es más que setenta.
• ¿Qué número es mayor?

No. In que, the u is silent.

So que is pronounced keh, not kweh.

This is a very common spelling pattern in Spanish:

• que = keh
• qui = kee

Because Spanish number words can act like nouns when you are talking about the numbers themselves.

So:

• Ochenta es más que setenta.

is like saying Eighty is more than seventy in English.

If the numbers were describing nouns, then they would work differently:

• ochenta libros
• setenta casas

But here they stand alone as numbers.

Not normally. Más grande is usually for physical size, not numerical value.

For numbers, use:

• más que
• mayor que

So these sound natural:

• Ochenta es más que setenta.
• Ochenta es mayor que setenta.

But más grande que would usually sound wrong or unnatural for a pure number comparison.

Yes. A very natural opposite version is:

• Setenta es menos que ochenta.

You can also keep the same meaning with a more mathematical style:

• Ochenta es mayor que setenta.

The basic Spanish comparison patterns are:

• más ... que = more than
• menos ... que = less than
• mayor que = greater than

Yes:

• 80 es más que 70.

That is completely normal in math, notes, exercises, and many everyday contexts.

In more formal writing, people often spell numbers out, especially at the beginning of a sentence, but using digits is very common when the sentence is mathematical.