B3 and B4 are as follows:B1 = 2 × B2B3 = 0.5 × B2B4 = B2 + 10 = B1 – 10.Inserting the value of B1 = 2 × B2.→ B2 + 10 = 2 × B2 – 10.B2 = 20.B4 = 20 + 10 = 30.Thus, WEIGHT of B4 is 30 KG.