F(a, b, c, d) = ab + cd Replace a with 4 , c with 2 , and d with 3 .
F(4, b, 2, 3) = 4b + 23
F(4, b, 2, 3) = 12 Replace F(4, b, 2, 3) with 4b + 23
4b + 23 = 12 23 = 8
4b + 8 = 12 Subtract 8 from both sides of the equation.
4b = 12 - 8
4b = 4
4b = 41
b = 1