What percentage above the cost price of an article should be marked so as to gain 25% after allowing a discount of 20%?

Correct option is D

Given:
Gain = 25%
Discount = 20%
Formula Used:
​$$\frac{\text{Marked Price}}{\text{Cost Price}} = \frac{100 + \text{Gain \%}}{100 - \text{Discount\%}}$$​​
Percentage Above Cost Price =  $$\left( \frac{\text{Marked Price}}{\text{Cost Price}} - 1 \right) \times 100\%$$​​
Solution:
​$$\frac{\text{Marked Price}}{\text{Cost Price}} = \frac{125}{80}$$​​
Marked Price = Cost Price × 1.5625
Percentage Above Cost Price = [(1.5625 ÷ 1) - 1] × 100%
Percentage Above Cost Price = (1.5625 - 1) × 100%
Percentage Above Cost Price = 0.5625 × 100%
Percentage Above Cost Price = 56.25%