Step-by-step explanation:
Power is defined as the rate at which work is done in per unit time.
Mathematically, 

It is given that work done by engine is 4,560,000 J and time is 20 minutes.
There is 60 seconds in 1 minute. So, convert minutes into seconds as follows. 
 

 = 1200 seconds
Calculate power output of the engine as follows.
 
 
 
 = 

 = 3800 J/s
 or, = 3800 Watt
Therefore, the power output of the engine is 3800 Watt.