Question:

A man buys an article for Rs 150 and makes overhead expenses which are 10% of the cost price. At what price must he sell it to gain 20%?

(a) Rs 182

(b) Rs 192

(c) Rs 198

(d) Rs 208

Solution:

​(c) Rs 198

$\mathrm{CP}=\mathrm{Rs} 150$

Total $\mathrm{CP}=\mathrm{Rs}(150+10 \%$ of 150$)$

$=\operatorname{Rs}\left(150+\left(\frac{10}{100} \times 150\right)\right)$

$=\operatorname{Rs}(150+15)$

$=\operatorname{Rs} 165$

$\therefore$ Desired $\mathrm{SP}=\left\{\frac{(100+\text { gain } \%)}{100} \times\right.$ total $\left.\mathrm{CP}\right\}$

$=$ Rs. $\left\{\frac{(100+20)}{100} \times 165\right\}$

$=$ Rs. $\left(\frac{120}{100} \times 165\right)$

$=$ Rs. 198