"You have to pay fifteen pesos."
Translation:Tienes que pagar quince pesos.
One thing I've notice, when translating from English to Spanish DL seems only to accept numbers that are written out. I assume it's because they want to make sure you actually know the numbers in Spanish.
If you wrote out QUINCE, and not the number 15 (as you've written above,) your answer looks correct to me.
@Margarita577545: I'm sure you've tried already (but wanted to be sure in case you haven't): when typing, hold down the "u" key. Does your keyboard not give any alternatives that include the desired accent? My default phone keyboard does, but I installed Google keyboard on my phone to better utilize common Spanish shortcuts (for example I have the regular n key as well as a key for ñ on its own), and a Spanish dictionary/spell check. Google keyboard is pretty amazing/worth checking out for a multitude of purposes aside from Duo, IMO. Hope this helps!
"to have to" do something (in this case pay) is an idiom in Spanish that requires "tener que" followed by an infinitive.
you have to pay the check = tienes que pagar la cuenta
I have to read the book = tengo que leer el libro
we have to cook dinner = tenemos que cocinar la cena
If you used "Tienes que pagar quince pesos" or "Tiene que pagar quince pesos", you are correct. If you were marked wrong, report it.
If you used "Tú tienes que pagar quince pesos" or "Usted tiene que pagar quince pesos", you would also be correct. If you were marked wrong, report it.
However if you used "Usted tienes que pagar quince pesos" or "Tú tiene que pagar quince pesos", you are incorrect and should be marked wrong. The subject pronouns do not agree with the verb conjugations.