Ayesha can complete a piece of work in 16 days. Amita can complete the same piece of work in 8 days. If both of them work together in how many days can they complete the same piece of work ?

Answer: Option B

Ayesha's 1 day's work $$=\frac{1}{16}$$
Amita's 1 day's work $$=\frac{1}{8}$$
(Ayesha + Amitha)'s 1 day's work
$$\begin{array}{rl}& =\frac{1}{16}+\frac{1}{8}\\ & =\frac{3}{16}\end{array}$$
∴ Both together can complete the work in
$$\begin{array}{rl}& =\frac{16}{3}\\ & =5\frac{1}{3}\text{ days}\end{array}$$