Question 248197
Romil can paint a fence in 4 hours, while Dina can do it in 5 hours.
 If the work together what part of the fence can they paint together in one hours? 
How long will it take them to finish painting the fence if they work together?
:
Find out how long to complete the job first.
:
Let t = time required when working together
Let the completed job = 1
:
{{{t/4}}} + {{{t/5}}} = 1
Multiply equation by 20, to get rid of the denominators, results:
5t + 4t = 20
9t = 20 
t = {{{20/9}}}
t = 2.22 hrs
:
In 1 hr they can paint {{{1/2.22}}} = .45 or 45% of the fence in 1 hr