In Exercises 13-20, find the value of x so that the function has the
given value.
13. f(x) = 6x; f(x) = -24
14. g(x) = -10x; g(x) = 15
15. f(x) = 3x – 5; f(x) = 4
16. h(x) = 14 – 8x; h(x) = -2