Evaluate for: a = 4, b = 8, c = -2

15). a (b + c) + b(a + c)

16).

Evaluate for: a = .5, b = 2, c = 4 (use a calculator!)

17). a b - 2 a c + a c

18).

Evaluate for: a = 4, b = 9, c = -5

19).

20).