Problem 2 - Reverse method

Ana saved a lot of money but decides to spend it. On the first day he spent a quarter of the money saved, the next day he spent half of the remaining amount, and on the third day half of the remaining amount. If $ 9 left, how much money did Ana have before she spent it?

Fill in here

Remember !

If the problems contain data that depend on each other then the reverse method is applied. The problem will be solved from the end to the beginning by performing the reverse operation.

Exemple !

Ana saved a lot of money but decides to spend it. On the first day he spent a quarter of the money saved, the next day he spent half of the remaining amount, and on the third day half of the remaining amount. If $ 9 left, how much money did Ana have before she spent it?

On the third day she had 9 x 2 = $ 18

The next day she had 18 x 2 = $ 36

In the first she had y - y / 4 = 36, because he spent a quarter of money

3y/4 = 36

y = 36 x 4 ÷ 3

y = 48

We verify to see if the exercise has been solved correctly

48 - 48 ÷ 4 = 48 - 12 = 36

36 ÷ 2 = 18

18 ÷ 2 = 9

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