10)
f(-1) = 2x - 1
f(-1) = 2.(-1) - 1
f(-1) = -2 - 1
f(-1) = -3
f(-4) = x - 1
f(-4) = -4 - 1
f(-4) = -5
11)
f(-4) = x
f(-4) = -4
f(0) = -x + 4
f(0) = -0 + 4
f(0) = 4
12)
f(-4) = 5
f(8) = -2x + 10
f(8) = -2.8 + 10
f(8) = -16 + 10
f(8) = -6
