Question

O,
Illustration 6 A can do a piece of work in 25 days. When he had worked for 5 days B
joined him. If they complete the work in 10 more days, in how many days can B alone finish
the work ?
​

Answer 1

A can do a piece of work in 25 days

So, he does 1/25 of a work per day

In six days he would have done

1/25 × 5= 5/25 work

Let x be the time B takes to finish a work

thus he completes 1/x per day

As per question,

5/25+[ 1/25 + 1/x]10=1

5/25+(x+25)/25x × 10= 1

5/25 +(10x+250)/25x=1

5x+10x+250= 25x

250= 25x-15x

10x= 250

x= 250/10= 25

Therefore, B takes 25 days to complete a work.