Question:
If the selling price of a TV set is equal to $\frac{6}{5}$ of its cost price, find the gain per cent.
Solution:
Let the CP of the TV set be ₹ $x$.
SP of the TV set $=\frac{6}{5} \mathrm{CP}=₹ \frac{6}{5} x$
Gain $=$ SP of the TV set $-$ CP of the TV set $=\frac{6}{5} x-x=$ ₹ $\frac{x}{5}$
Gain $\%=\frac{\text { Gain }}{\text { CP }} \times 100 \%=\frac{\frac{x}{5}}{x} \times 100 \%=\frac{100}{5} \%=20 \%$