A student buys a toy for Rs. 200 and sells it for Rs. 225. Find his gain per cent.

Given: Cost price of the toy = Rs. 200

Selling price of the toy = Rs. 225

We know that,

Gain = Selling price − Cost price = 225 − 200 = Rs. 25

By using the formula,

Gain per cent $=\frac{\mathrm{Gain}}{\mathrm{Cost} \mathrm{price}}\times 100$

$=\frac{25}{200}\times 100$

$=12.5\%$