Question

Two friends a and b working together can complete an assignment in 4 days. if a can do the assignment alone in 12 days, in how many days can b alone do the assignment ?

Answer 1

The statement given that, "A and B working together can complete an assignment in 4 days" .

So (A+B)'s 1 day's work = $\frac{1}{4}$

A alone can complete the assignment in 12 days.

That is A's 1 day's work = $\frac{1}{12}$

Therefore B's one day's work= Combine work of A and B - A's 1 day's work

$=\frac{1}{4}-\frac{1}{12}$

Now take the LCM of 12 and 4

$LCM(4,12)=12$

Hence B's 1 day's work $=\frac{1}{4}-\frac{1}{12}\\=\frac{3}{12}-\frac{1}{12}\\=\frac{2}{12}\\=\frac{1}{6}$

Hence B alone can complete an assignment work in 6 days.