The marked price of a watch was Tk. 720. A man bought the same for Tk. 550.80 after getting two successive discounts. the first being 10%. then the second discount rate is-

Question: The marked price of a watch was Tk. 720. A man bought the same for Tk. 550.80 after getting two successive discounts. the first being 10%. then the second discount rate is-

Solution:
Marked price = 720
Actual price = 550.80
First discount = 10%
Let the second discount be x%
Then, we can write
⇒ 720(1 - 0.1)(1 - x/100) = 550.80
⇒ 720 × 0.9(1 - 0.01x) = 550.8
⇒ 648(1 - x/100) = 550.8
⇒ 1 - x/100 = 550.8/648
⇒ x/100 = 1 - 0.85
⇒ x/100 = 0.15
⇒ x = 0.15 × 100
∴ x = 15

∴ Second discount = 15%