Question

A alone can do a peace of work in 7 days and B alone can do the work in 8 days . if both of them work together, how long will they take to complete the work ? 

A 48/11
B 56 days
C 56/15 days
D none of these​

Answer 1

A alone can do a peace of work in 7 days and B alone can do the work in 8 days . if both of them work together, how long will they take to complete the work ? 

A 48/11

B 56 days

C 56/15 days

D none of these

Answer 2

Answer:

A's 1 day's work = $\sf\dfrac{1}{7}$

B's 1 day's work = $\sf\dfrac{1}{8}$

∴Both A and B's 1 day's work = $\sf\dfrac{1}{7}$ + $\sf\dfrac{1}{8}$

∴ $\sf\dfrac{8+7}{56}$

$\sf\dfrac{15}{56}$

Hence, None of these.