Hola Juanita
I imagine you are referring to this question using the pronoun "ustedes":
¿ ___ ustedes descuentos?
(Do you offer discounts?)
The pronoun ustedes, that is a formal you plural takes the verb in the ellos form, not the vosotros form, therefore here we need "hacen", as in ellos hacen, not "hacéis".
Saludos
Inma