A and B can do a piece of work in 72 days B and C in 120 days and A and C in 90 days in what time can A alone do it
Answers
B and C takes 120 days
A and C takes 90 days
No.of days taken by B,C and A,C all together =120+90
=210 days
A and B does the work in 72 days
number of days taken C by working two times =210- 72
=138
number of days taken by C =138÷2
=69
number of days taken by A and C together =90
number of days taken by A=90-69
=21
Step-by-step explanation:
(A+B)'s 1day work =1/72
(B+C)'s 1 day work =1/120
(C+A)'s 1 day work =1/90
adding all three , 2(A+B+C)'s 1 day work =1/72+1/120+1/90
=5+3+4/360
=12/360
=1/30
(A+B+C)'s 1 day work =1/60
Now ,A's one day work =(A+B+C)'s 1 day work - (B+C)'s 1 day work
=1/60-1/120=2-1/120
=1/120
Hence , A can complete the work in 120 days.
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