Motor Efficiency: Understand Why 0.85 Matters

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The discussion revolves around the calculation of motor efficiency using the formula P=F*v, where P represents motor effect. The user is confused about whether to multiply or divide by the efficiency factor of 0.85 when calculating true power output. It is suggested that the problem may involve determining the motor's input power based on a known output power after accounting for efficiency. Clarification is needed on whether the given power is the final output or the initial motor power. Understanding this distinction is crucial for accurate calculations.
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In an assigment I'm using the general formula P=F*v, where P is the effect of a motor. The motor drives something through a series of sprockets, who's efficiency is 85 %, and so it seems intuitive to me to multiply the resulting P with 0,85 to get true effect, but apparently the solution divides by 0,85 which results in a higher P than to begin with. I don't get the logic in this, so if someone can explain why this is correct I would like to hear it.
 
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What's the question?
Could it be that you're given the final output power (that is, after the sprockets), and asked the power of the motor?
 

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