Question 389578
a) If a hose can fill a tank in 20 minutes, then it can fill {{{1/20}}} of the tank in 1 minute.
If a hose can fill a tank in 12 minutes, then it can fill {{{1/12}}} of the tank in 1 minute.
Do you see the pattern here?
b) If both hoses are running for 1 minute, then just add the rate/minute for each hose.
{{{(1/20)+(1/12) = (3/60)+(5/60)}}}={{{8/60 = 0.133}}}minutes.
c)If both hoses are running together, then the rate per minute is {{{8/60 = 2/15}}} so {{{2/15}}} of the tank will be filled in 1 minute.
So it will take {{{15/2 = 7.5}}} minutes to fill the tank.