f(x) = 15x + 4
x = -3: f(x) = 15x + 4
f(-3) = 15(-3) + 4
f(-3) = -45 + 4
f(-3) = -41
(x, f(x)) = (-3, -41)
x = 0: f(x) = 15x + 4
f(0) = 15(0) + 4
f(0) = 0 + 4
f(0) = 4
(x, f(x)) = (0, 4)
x = 2: f(x) = 15x + 4
f(2) = 15(2) + 4
f(2) = 30 + 4
f(2) = 34
(x, f(x)) = (2, 34)
