A dealer purchased a fan for Rs 1080.

Solution:

Cost price of the fan $=R s 1080$

Gain percentage $=25 \%$

$\therefore$ Selling price $=\left\{\frac{(100+\text { gain } \%)}{100} \times \mathrm{CP}\right\}$

$=\left\{\frac{100+25}{100} \times 1080\right\}$

$=\frac{125}{100} \times 1080$

$=$ Rs 1350

Let the marked price be Rs $x$.

Discount $=25 \%$ of $R s x$

$=\frac{25 x}{100}$

SP = MP − discount

$\Rightarrow 1350=X-\frac{25 X}{100}$

$\Rightarrow 1350=\frac{100 x-25 x}{100}$

$\Rightarrow 135000=75 x \Rightarrow x=\frac{13500}{75} \Rightarrow x=1800$

Therefore, the marked price of the fan is $R s 1800$.