Two bodies of masses 12 ~kg and 6 ~kg are projected simultaneously with velocities 15 ~ms ⁻¹ and 20 ~ms ⁻¹ respectively from the top of a tower of height 25 ~m . The body of mass 12 ~kg is projected vertically upwards and the body of mass 6 ~kg is projected horizontally. The maximum height reached by the centre of mass of the system of two bodies from the ground. ( g =10 ~ms ⁻² )