Discussion of Question with ID = 044 under Time-and-Work

This is the discussion forum for this question. If you find any mistakes in the solution, or if you have a better solution, then this is the right place to discuss. A healthy discussion helps all of us, so you are requested to be polite and soft, even if you disagree with the views of others. The question and its current solution has also been given on this page.

Advertisement

Question

A can do a work in 3 days. B can destroy the work in 7 days. In how many days will they together complete the work?

A

$5{1/4}$ days.

B

$6{1/4}$ days.

C

$7{1/4}$ days.

D

$8{1/4}$ days.

Soln.
Ans: a

Putting x = 3 and y = 7 in the shortcut method, we get ${xy}/{y - x}$ = ${21/4}$, which is same as: $5{1/4}$.


Comments and Discussion