A water purifier is on sale for 10% discount on the original price. A store-wide sale results in an additional discount of 15%. What is the total discount on the original price?

23.50%

Two successive discounts of a% and b% = a + b - $\frac{a \times b}{100}$

Final discount after two successive discounts of 10% and 15%  

                           =  10 + 15 - $\frac{10 \times 15}{100}$

                           = 25 - 1.5 = 23.50%