John spent \({2\over 7}{}{}\) of his money on 4 rulers and 8 pens. He then spent the remaining amount of money on 6 rulers, 7 books and 12 pens. How many books could he buy with \( {6 \over 7}{}{}\) of his money?

Robtlukas Aug 14, 2021

#2**0 **

John can use \(\frac{1}{7}\)of his money to buy 2 rulers and 4 pens.

John can also \(1 - \frac{2}{7} = \frac{5}{7}\)of his money to buy 6 rulers, 7 books, and 12 pens.

We could also see that he can buy 6 rulers and 12 pens using \(\frac{1}{7} \times 3 = \frac{3}{7}\)of his money.

7 books cost \(\frac{5}{7} - \frac{3}{7} = \frac{2}{7}\)of his money.

\(7 \times 3 = \boxed{21}\)

Capban Aug 14, 2021