2(a + b) + ab = 16 ... (1) 2(b + c) + bc = 24 ... (2) 2(c + a) + ca = 31 ... (3) From equation (2), equation (3) ⇒ (a - b) (2 + c) = 7 ... (4) From equation (2) and equation (4) ⇒ 4a = 2 + 5b ... (5) Solve equation (1) and (5) b = 2 a = 3, c = 5 Volume = 30