(3) Sum of weights of A, B and C is 84 × 3 = 252 kg Sum of weights of A, B, C and D is 80 × 4 = 320 kg Now, D’s weight is 320 – 252 = 68 kg. So, E’s weight will be 68 + 3 = 71 kg Sum of weights of B, C, D and E is 79 × 4 = 316 kg Therefore, weight of A is, “Sum of weights of A, B, C, D and E – Sum of weights of B, C, D and E” that is (252 + 68 + 71) – 316 = 75 kg