Problema Solution
A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :
Answer provided by our tutors
A can do a work in 15 days means the rate of a is: 1/15 per day
B can do a work in 20 days means the rate of a is: 1/20 per day
If they work on it together for 4 days the will finish:
4/15 + 4/20 = 7/15
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the fraction of the work that is left is:
1 - 7/15 = 15/15 - 7/15 = (15 - 7)/15 = 8/15.