Answer: Factory A produces 30 more machines than factory B.
Explanation:
The data that we have is:
Factory A produces 45 machines in 20 minutes, this is 45/20 machines per minute = 2.25 machines per minute
Factory B produces 30 machines in 15 minutes, this is 30/15 machines per minute = 2 machines per minute.
then, if both factories work for two hours (2 hours is equal to 120 minutes)
we have that factory A produces:
N = (2.25 machines per minute)*120 mins = 270 machines
and factory B produces:
M = (2 machines per minute)*120 mins = 240 machines
So factory A produce 270 - 240 = 30 more machines