Question 807123
If it takes 3 boys an hour to clean their bedroom,
 how long would it take 4 boys to clean the same room?
:
It would take 1 boy three times as long to clean the room; 3 hrs.
Let the completed job = 1
Let t = time for 4 boys to do the job
{{{t/3}}} + {{{t/3}}} + {{{t/3}}} + {{{t/3}}} = 1
multiply equation by 3 to clear the denominators
t + t + t + t = 3
4t = 3
t = 3/4 of an hr or 45 min