Question 331746
one hose takes 42 minutes
so it does 1/42 of the job in 1 minute.
..
the other fills in 30 minutes
so it does 1/30 of the job in 1 minute
.
together they can do 1/30+1/42 of the job in 1 minute
..
30+42/ 32*40 of the job in 1 minute
72/1280 
So they will together fill the tank in 1280/72= 17.7 minutes