If an item is given two successive discounts of 10% and 15%, what is the total effective discount?

25%

20%

23.5%

24.5%

Explanation

The total discount is not simply added. Use the formula:
Effective discount = $a + b - frac{ab}{100}$

$10 + 15 - frac{10 times 15}{100} = 25 - 1.5 = 23.5%$