The price of an article is first increased by 20% and later on decreased by 25% due to reduction in sales. Find the net percentage change in final price of the article?

Let the price of article is Rs. 100
First increase % = 20%
After increase, price of article
$$\eqalign{ & = 100 \times \frac{{120}}{{100}} \cr & = {\text{Rs}}{\text{.120 }} \cr} $$
Second decrease % = 25%
After decrease, price of article
$$\eqalign{ & = 120 - \frac{{120 \times 25}}{{100}} \cr & = {\text{Rs}}{\text{. }}90 \cr} $$
Net change percent in price
$$\eqalign{ & = \frac{{100 - 90}}{{100}} \times 100 \cr & = \frac{{10}}{{100}} \times 100 \cr & = 10\% \cr} $$