Answer: Option C
Let the total number of eggs bought be a
10% of eggs are rotten
∴ Remaining eggs :
$$\eqalign{
& = a - 10\% {\text{ of }}a \cr
& = a - \frac{{10a}}{{100}} \cr
& = \frac{{100a - 10a}}{{100}} \cr
& = \frac{{90a}}{{100}} \cr
& = \frac{{9a}}{{10}} \cr} $$
Man gives 80% of $$\frac{{9a}}{{100}}$$ eggs to his neighbour
$$\eqalign{
& = \frac{{80}}{{100}} \times \frac{{9a}}{{10}} \cr
& = \frac{{72a}}{{100}} \cr} $$
Remaining eggs :
$$\eqalign{
& = \frac{{9a}}{{10}} - \frac{{72a}}{{100}} \cr
& = \frac{{90a - 72a}}{{100}} \cr
& = \frac{{18a}}{{100}} \cr
& = \frac{{9a}}{{50}} \cr} $$
According the question,
$$\eqalign{
& \Rightarrow \frac{{9a}}{{50}} = 36 \cr
& \Rightarrow 9a = 36 \times 50 \cr
& \Rightarrow a = \frac{{36 \times 50}}{9} \cr
& \Rightarrow a = 200 \cr} $$
Hence, the total number of eggs bought be = 200