Question

A & B can together do a piece of work in 10 days .B alone can do it in 20 days .In how many days can A alone do it?​

Answer 1

Answer:

work done by A and B in 1 day = 1/10

work done by B in 1 day = 1/20

work done by A in 1 day = 1/x (let)

we know that

$\frac{1}{x} + \frac{1}{20 } = \frac{1}{10} \\ \frac{20 + x}{20x} = \frac{1}{10} \\ 20 + x \: = 2x \\ x = 20$

A alone can do it in 20 days