A shopkeeper allows 20% off on the marked price of goods and still gets a profit of 25%.

Given:

MP of an article $=$ Rs. 500

Discount $=20 \%$

There fore, Discount $=20 \%$ of 500

$=0.20 \times 500$

$=100$

So, SP $=\mathrm{MP}-$ Discount

$=$ Rs. $(500-100)$

$=$ Rs. 400

$\mathrm{CP}=\left[\frac{100}{(100+\text { Gain } \%)} \times \mathrm{SP}\right]$

$=\left[\frac{100}{(100+25)} \times 400\right]$

$=\frac{40000}{125}$

$=$ Rs. 320

Thus, the actual cost of the article is Rs. 320 .