Help please, power (piano pulled up by workers through pulley)

[xregina12]

A 3.50 kN piano is lifted by 3 workers at constant speed to an apartment 25 m above ground. Each worker is able to deliver 165 W of power and the pulley is 75% efficient (25% lost due to friction on pulley). Neglecting mass of pulley, what is the time required to lift the piano from the street to the apartment.
I know that F=T-mg=ma=0
T=3500N
Work=3*165=495W=F/t
But I'm not really sure how to sort this problem out and incorporate the 75% efficiency of the pulley and the height above ground. Please help me.

 

[Redbelly98]

Work=3*165=495W=F/t

Not quite. You are equating work (units: Joules) with power (units: Watts) here, but they are not the same. And neither of those would equal force/time.

At any rate, 495W is the power exerted by the 3 people. So how much of that power gets transmitted to the piano? (hint: it is not 100% of the power)