Question

A can fo a piece of work int 10 days and b can do the same work in 20 days

Answer 1

Formula: If 'A' can finish a piece of work in x days and 'B' can finish the same work in y days, then A and B together will finish the work
$( \frac{xy}{x + y} ) \: days$
Solution: Here, x = 10 and y = 20
Then,

$( \frac{xy}{x + y} ) = ( \frac{10 \times 20}{10 + 20} ) \\ \: \: \: \: \: \: \: \: \: \: = ( \frac{200}{30} ) = 6 \frac{2}{3} days$