How many total years during one's teen years is a person age thats a prime number?

If f(x)=x^3 and g(x)=2x+7 when g(x)=-5

How do you solve a question like this?

Abag contains 4 red, 7 blue and 5 yellow marbles. event a is defined as drawing a yellow marble on the first draw and event b is defined as drawing a blue marble on the second draw. if two marbles are drawn from the bag, one after the other and not replaced, what is p(b|a) expressed in simplest form? a. 7/16 b. 7/15 c. 14/16 d. 14/15