Question

find the single discount equilant to two successive discount of 20% and 10%.

Answer 1

Let original price = 100
After 20% discount = 100 - 20 = 80

10% of 80 = 10/100 × 80 = 8
After 10% discount = 80-8 = 72

Total discount = 100-72 =28
Equivalent discount = 28/100 × 100 = 28%

Equivalent discount is 28%

Answer 2

Consider a product, whose price is Rs. 100/-
Let's apply two successive discounts on it,
(i) 20 % :  The product's price is now : Rs. 80/-  (1% of 100 is 1, 20% is 20)
(ii) 10 % :  The product's price is now Rs. 72/- (1% of 80 is 0.8, 10% is 8)

Now, to % of single discount on the product, that makes its price Rs. 72/- is 28%