News from Mathnasium of Ealing

Question: After a 15% discount and 6% sales tax, a book costs £27.03. What is the book’s sticker price?

Answer: £30.00

Solution: First, we undo the tax. When the book was taxed, its value was multiplied by 1.06. So, we divide: £27.03 ÷ 1.06 = £25.50. Now, we undo the discount. When the discount was applied, the value of the book was multiplied by 1 – 0.15 = 0.85. So, we want to divide again: £25.50 ÷ 0.85 = £30.00. The book’s sticker price is £30.00.