Question 1034848
Call the times used by each, m and b.  Then we can write
b + m = 50  and
30b + 35m = 1650
Now multiply the top one by 30 and subtract from the bottom one...we get

30b + 35m = 1650
-(30b + 30m = 1500)
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5m = 150
m = 30 hours for Moore so that
b = 20 hours for Bennett