Math problem with 4/7ths being the answer

In a class, there are 12 girls. if the ratio of boys to girls is 5: 4 how many boys are there in the class

Rewrite the following quadratic functions in intercept or factored form. show your work. y = 4x^2 - 19x- 5

Which sum or difference identity would you use to verify that cos (180° - q) = -cos q? a.) sin (a -b) = sin a cos b – cos a sin b b.) cos (a -b) = cos a cos b – sin a sin b c.) cos (a -b) = cos a cosb + sin a sin b d.) sin (a + b) = sin a cos b + cos a sin b