A painter of mass 1100 kg stands on a platform of mass 600 k

A painter of mass 110.0 kg stands on a platform of mass 60.0 kg and pulls himself up by two ropes that hang over pulleys, as shown. The painter pulls each rope with a force of 750.0 N and accelerates uniformly with acceleration a. The acceleration a can be either positive (up) or negative (down).What is a, neglecting the fact that no one could do this for long? (positive is up)

Solution

taking man and platform as a system then
applying Fnet = ma on this system in vertical direction,

4T - Mg - mg = (M + m)a

4(750) - (110 + 60)(9.8)= (110 + 60)a

1334 = 170a

a = 7.85 m/s^2