Question

Задача: цена на стиральные машины в мае упала на 15% и стала 6640руб, а в сентябре увеличилась на 20%. Сколько стоили стиральные машины до понижения и сколько они стали стоить в сентябре?

Answer 1

Пусть цена была х руб

0,85х=6640руб - в мае она стала 

х=6640/0,85

х= 7811,76 руб - была цена до мая

6640+0,2*6640=6640+ 1328=7968 руб - цена в сентябре

Ответ. 7811,76 руб и 7968 руб 

Answer 2

Calculation of the original price of washing machines and the price in September:

To calculate the original price of the washing machines and the price in September, we can use the information given in the question.

Let's assume the original price of the washing machines is represented by x.

According to the question, the price of the washing machines in May decreased by 15% and became 6640 rubles. This can be represented by the equation:

x - 0.15x = 6640

Simplifying the equation, we get:

0.85x = 6640

Dividing both sides of the equation by 0.85, we find:

x = 6640 / 0.85

Using a calculator, we can determine that the original price of the washing machines was approximately 7811.76 rubles.

Now, let's calculate the price of the washing machines in September. According to the question, the price increased by 20%. We can represent this as:

1.20 * x

Substituting the value of x we found earlier, we get:

1.20 * 7811.76

Using a calculator, we can determine that the price of the washing machines in September was approximately 9374.11 rubles.

Therefore, the washing machines originally cost around 7811.76 rubles and they cost around 9374.11 rubles in September.