Learn Italian: Ho già pagato la mia bolletta, non è giusto pagare anche la tua. - I already paid my bill, it's not fair to also pay yours.

In Italian, independent possessive pronouns (words like "mine", "yours", "hers" that stand alone without a noun) almost always need a definite article like il or la before them. Since it replaces la tua bolletta (your bill), we keep the article and say la tua.

How do I know whether to use il tuo, la tua, i tuoi, or le tue here?

Possessive pronouns must match the gender and number of the noun they are replacing, not the person who owns it. Here, "yours" refers to "your bill". Because bolletta (bill) is feminine and singular, the pronoun must be feminine and singular as well: la tua.

Why is già (already) placed in the middle of the verb ho pagato?

Common adverbs of time like già (already), ancora (yet), and mai (never) are usually placed right between the helping verb (ho) and the past participle (pagato) when using the past tense (passato prossimo).

Why is the second "pay" translated as the infinitive pagare?

When you use an impersonal expression like non è giusto (it is not fair), the verb that follows stays in its infinitive (dictionary) form because you are making a general statement rather than conjugating the verb for a specific person.