Question:
Tick (✓) the correct answer:
A bookseller sells a book for Rs 100, gaining Rs 20. His gain per cent is
(a) 20%
(b) 25%
(c) 22%
(d) none of these
Solution:
(b) 25%
$\mathrm{CP}=\mathrm{SP}-\mathrm{Gain}$
$=\mathrm{Rs}(100-20)$
$=\mathrm{Rs} 80$
$\therefore$ Gain percentage $=\left(\frac{\text { gain }}{\mathrm{CP}} \times 100\right) \%$
$=\left(\frac{20}{80} \times 100\right) \%$
$=25 \%$