Gary ate 21/25 of his candy bar. What percent of the candy bar did Gary eat?

I'm terrible at math any here is appreciated.

Marya wants to factor the polynomial 36x^3 -22x^2 - 144x.which term can she add to the polynomial that would not change its grestest common factor? check all that apply

What are the soultion(s) to the quadratic equation 40- x^2=0