The weight of X, in kg, is denoted by [X]. The weights of A, B, C, D, P, Q, R and S are measured. Given: A + B + C + D = 17 A + C = 6 P + Q + S + D = 15 P + Q + R + B = 17 P = R and Q = S B + D = 11 Which one of the following statements is correct?