Question

a can do a piece of work in 25 days B alone can do in 20 days a start the work and was joined by b after 10 days the work list for

Answer 1

a(10)+(a+b)x=1
1/25×10 +(1/25 +1/20)x=1
10/25+(1/25 +1/20)x=1
(1/25+1/20)x=1-10/25
(4+5/100)x=15/25
9x/100=15/25
9x=15×100/25
9x=15×4
9x=60
x=60/9
x=6.6 days
a+b can do in 6.6 days

Answer 2

Answer is 9/100.
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