Abhishek ordered 6 pair of red shoes and some pair of books. The price of a pair of red shoes is double than that of a pair of book. While preparing the bill the shopkeeper interchanged the number of pair of shoes and books by mistake which increased the bill by 40%. What was the ratio of the number of pair of red shoes and the number of pair of books in the original order?
Abhishek ordered 6 pair of red shoes and some pair of books. The price of a pair of red shoes is double than that of a pair of book. While preparing the bill the shopkeeper interchanged the number of pair of shoes and books by mistake which increased the bill by 40%. What was the ratio of the number of pair of red shoes and the number of pair of books in the original order? Correct Answer 1 : 3
Given :
Abhishek ordered 6 pair of red shoes and some pair of books
Formula used :
Total bill = Number of pair of red shoes × Price of a pair of red shoes + Number of pair of book × Price of a pair of a book
Calculation :
Let the number of pair of books be x.
Price of pair of red shoes : Price of pair of book = 2y : y
For first condition,
Total bill = Number of pair of red shoes × Price of pair of red shoes + Number of pair of book × Price of pair of book
⇒ Total bill = 6 × 2y + xy
⇒ Total bill = y(12 + x)
For second condition,
The shopkeeper interchanged the number of pair of shoes and pair of books by mistake.
Total bill = Number of pair of red shoes × Price of pair of red shoes + Number of pair of book × Price of pair of book
⇒ Total bill = x × 2y + 6y
⇒ Total bill = 2xy + 6y
According to question:
140% × (12 + x)y = 2y(x + 3)
⇒ 84 + 7x = 10x + 30
⇒ 3x = 54
⇒ x = 18
∴ The ratio of the number of pair of red shoes and the number of pair of books in the original order = 6 : x = 6 : 18 = 1 : 3