Question 1095596
 Isaac alone can do a piece of work in 5 days, and his wife, Esther also can do it in 8days.
if they work together, how long will it take them to complete the job.
:
let t = time required when working together
let the completed job = 1
:
Each will do a fraction of the job, the two fractions add up to 1
{{{t/5}}} + {{{t/8}}} = 1
multiply equation by the least common multiple of 5 and 8
40*{{{t/5}}} + 40*{{{t/8}}} = 40
Cancel the denominators
8t + 5t = 40
13t = 40
t = 40/13
t = 3.077 days