What is the y-value when x equals - 15?

Let f(x) = 3 − x . find the average rate of change of f(x) from x = a to x = a + h and simplify your answer so that no single factor of h is left in the denominator.

15/16 as a decimal rounded to the nearest hundredth

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)