Here, you are given too much information and you don't need all. You can use a simple formula for power to calculate. You don't need the masses of crane or object.

P = F.v

here, F is the resistance force, F= 1200N
v is the velocity at which the mass is moving, v = 0.2 m/s

So power = 1200 × 0.2 = 240 W