zwrócić opłatę in English:

I pay back £50 of the loan to the bank every month.

Did I pay back the money I borrowed from you?

You can pay back the loan over a period of three years.

She couldn’t borrow money from the bank, because bank don't belive that she will pay back.

She couldn’t borrow money from the bank, because the bank doesn't belive that she will pay back.