Question

A and B can do a piece of work in 15 days. A alone can finish it in 20 days. How many days will B alone take to finish the same work

Answer 1

Answer:

25

Step-by-step explanation:

As work done by A+B=15 days,

& Work done by A alone=20 days, means B can help A to do 5days work

Therefore B alone will take (Work done by A+B) + (Work done by B alone)=

which equals to 20+5=25!

Answer 2

Answer :-

B alone can finish the same work in 60 days.

Explanation :-

Since A alone can finish the work in 20 days,

•°• Work done by A in 1 day = 1/20

Let B does the same work in 'x' days.

•°• Work done by B in 1 day = 1/x

Work done by A and B in 1 day = 1/20 + 1/x

According to the question,

$= > 15( \frac{1}{20} + \frac{1}{x} ) = 1 \\ = > 15( \frac{x + 20}{20x} ) = 1 \\ = > 15x + 300 = 20x \\ = > 300 = 20x - 15x \\ = > 300 = 5x \\ = > x = \frac{300}{5} \\ = > x = 60 \: days$

Hence, B alone can finish the same work in 60 days.