Question

Мальчик в магазине потратил на покупку карандашей 10 % имеющихся у него денег, а на тетради 4/9 (дробь) оставшейся суммы. После покупки у него осталось 75 рублей. Сколько денег было у мальчика первоначально?

Answer 1

Получается, 75 - это 5/9 оставшейся от 1 покупки
1)(75/5)*9= 135 - сумма, которая осталась после покупки карандашей
2)135 - 90%
х - 100%
х=(135*100)/90
х=150
Ответ: 150 первоначальная цена

Answer 2

Problem Analysis

A boy spent 10% of his money on pencils and 4/9 of the remaining amount on notebooks. After the purchase, he had 75 rubles left. We need to determine the initial amount of money the boy had.

Solution

Let's assume the initial amount of money the boy had is x rubles.

The boy spent 10% of his money on pencils, which is 10/100 * x = x/10 rubles.

The remaining amount of money after buying pencils is x - x/10 = (10x - x)/10 = 9x/10 rubles.

The boy then spent 4/9 of the remaining amount on notebooks, which is (4/9) * (9x/10) = 4x/10 = 2x/5 rubles.

The remaining amount of money after buying notebooks is (9x/10) - (2x/5) = (9x - 4x)/10 = 5x/10 = x/2 rubles.

According to the problem, the boy had 75 rubles left, so we can set up the equation:

x/2 = 75

To find the value of x, we can multiply both sides of the equation by 2:

x = 75 * 2 = 150

Therefore, the initial amount of money the boy had was 150 rubles.

Answer

The initial amount of money the boy had was 150 rubles.