Question 279379
That really depends on whether the apprentice knows what he is doing!
Considering they only saved 10 minutes with the apprentice's help I would not expect much from him.

40/50+40/x=1
4/5+40/x=1
40/x=1/5
200=x
200/60=3 hr 20 minutes
check
40/50+40/200=1
4/5+1/5=1
1=1
ok