Question 594695
The carpenter can do 1/5 the job in 1 hr.
2/5 the job done in 2 hrs. 1 - 2/5 = 3/5 of the job remains.
1/5 + a = 3/5 in one hr.
a = 2/5
The assistant working alone would take 5/2 = 2.5 hrs to do the job.
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Ed