# X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4...........

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X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last?

posted Feb 18, 2016

+1 vote

4(1/20)+x(1/20+1/12)=1
12/60+x(3/60+5/60)=1
3/15+x(2/15)=1
2x/15=1-3/15 *15
2x=15-3
2x=12 /2
x=6
the answer is 6 days of working together and 4 days x alone
10 days in sum

answer Feb 20, 2016
–1 vote

A AND B WORK ANOTHER 10 DAYS TO FINISH THE BALANCE OF WORK 4/5

answer Feb 19, 2016
–1 vote

X started the work alone for 4 days, doing 4/20, or 1/5 of the work, leaving 4/5ths of the work to be done. Let n be the amount of days X and Y worked together. Then:
n/20+n/12=4/5
3n+5n=48
8n=48
n=6 days of working together to finish the job
☺☺☺☺

answer Jan 12, 2018 by anonymous

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