A box is being lifted by a crane...torque question

A 1.60 multiplied by 10^2-kg piano is being lifted at a steady speed from ground level straight up to an apartment 18.0 m above the ground. The crane that is doing the lifting produces a steady power of 4.00 multiplied by 102 W. How much time does it take to lift the piano?

160kg x 9.8 = 1568N. weight.
Work done raising piano 18m = (1568 x 18) = 28,224 Joules.
(28,224/400W) = 70.56 secs.