Find the measure of ∠D if
∠A = 5/2x + 16
∠B = 7/2x + 20
∠C = 3/2x + 68
∠D = 3/2x + 40
∠A = 5/2x + 16
∠B = 7/2x + 20
∠C = 3/2x + 68
∠D = 3/2x + 40