Question

Nosotros ___________________ el pelo con el cepillo. (cepillarse)

Answer 1

You want to change cepillarse to the nosotros form:

Nosotros cepillamos el pelo con el cepillo.
You should get cepillamos as your answer.
Hopefully that helped! :)

Answer 2

Nosotros _______nos cepillamos____________ el pelo con el cepillo.