Question

За 2 блокнота ,5карандашей и3 ручки заплатили 119 руб. Найди цену блокнота, карандаша и ручки , если за 2 блокнота и 5 карандашей заплатили 83 рубля , а за 5 карандашей и 3 ручки -81 руб.

Answer 1

2бл+5кар+3руч=119руб
2бл+5кар=83руб
5кар+3руч=81руб

1)) {2бл+5кар+3руч}- {2бл+5кар}=
119- 83= 36руб стоят 3 ручки

2)) 36:3= 12руб стоит ручка

3)) {2бл+5кар+3руч} - {5кар+3руч}=
119- 81= 38руб стоят 2 блокнота

4)) 38:2=17 руб стоит блокнот

5)) {5кар+3руч} - 3 ручки=
81-12•3= 81-36= 45руб стоят 5 карандашей

6)) 45:5= 9руб стоит карандаш

Ответ: блокнот стоит 17 рублей, ручка стоит 12 рублей, карандаш стоит 9 рублей

Answer 2

Calculation of Prices

To find the prices of the notebooks, pencils, and pens, we can set up a system of equations based on the given information.

Let's assume the price of a notebook is x rubles, the price of a pencil is y rubles, and the price of a pen is z rubles.

From the given information, we can set up the following equations:

Equation 1: 2x + 5y + 3z = 119 Equation 2: 2x + 5y = 83 Equation 3: 5y + 3z = 81

To solve this system of equations, we can use substitution or elimination method. Let's use the elimination method to find the values of x, y, and z.

Solving the System of Equations

To eliminate the variable x, we can subtract Equation 2 from Equation 1:

(2x + 5y + 3z) - (2x + 5y) = 119 - 83

Simplifying the equation, we get:

3z = 36

Dividing both sides of the equation by 3, we find:

z = 12

Now, we can substitute the value of z into Equation 3 to find the value of y:

5y + 3(12) = 81

Simplifying the equation, we get:

5y + 36 = 81

Subtracting 36 from both sides of the equation, we find:

5y = 45

Dividing both sides of the equation by 5, we get:

y = 9

Finally, we can substitute the values of y and z into Equation 2 to find the value of x:

2x + 5(9) = 83

Simplifying the equation, we get:

2x + 45 = 83

Subtracting 45 from both sides of the equation, we find:

2x = 38

Dividing both sides of the equation by 2, we get:

x = 19

Calculation Results

Based on the calculations, we have found the following prices:

- The price of a notebook is 19 rubles. - The price of a pencil is 9 rubles. - The price of a pen is 12 rubles.

Please note that these calculations are based on the given information and the assumption that the prices of the items are constant.