Let A, B, C, D and E in kg. represent their respective weights. Then, ∴ A + B + C = 84 × 3 = 252 kg. A + B + C + D = 80 × 4 = 320 kg. ∴ D = (320 – 252) kg. = 68 kg. E = 68 + 3 = 71 kg. B + C + D + E = 79 × 4 = 316 kg. Now, (A + B + C + D) – (B + C + D + E) = 320 – 316 ⇒ A – E = 4 kg. ⇒ A = 4 + E = 4 + 71 = 75 kg.