Question

Булочка и стакан молока вместе стоят 12 рублей .., а две булочки и стакан молока стоят 17 рублей. Сколько стоит булочка? Сколько стоит стакан молока?

Answer 1

1) 17 - 12 = 5 ( рублей ) - стоит булочка
2) 12 - 5 = 7 ( рублей ) - стоит стакан молока

Answer 2

Solution:

To solve this problem, we can use a system of linear equations. Let's denote the cost of one bun as x and the cost of one glass of milk as y. We can then form the following equations based on the given information:

1. Equation 1: One bun and one glass of milk together cost 12 rubles. 2. Equation 2: Two buns and one glass of milk together cost 17 rubles.

We can then solve these equations to find the values of x and y.

Equations:

1. Equation 1: x + y = 12 2. Equation 2: 2x + y = 17

Solving the Equations:

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

Adding Equation 1 and Equation 2 together, we get: x + y + 2x + y = 12 + 17 3x + 2y = 29

Now, we can use this result to solve for x and y.

Calculations:

3x + 2y = 29 3x = 29 - 2y x = (29 - 2y) / 3

Now, we can substitute the value of x into Equation 1 to solve for y.

(29 - 2y) / 3 + y = 12 29 - 2y + 3y = 36 29 + y = 36 y = 36 - 29 y = 7

Now that we have the value of y, we can substitute it back into Equation 1 to solve for x.

x + 7 = 12 x = 12 - 7 x = 5

Conclusion:

So, the cost of one bun is 5 rubles and the cost of one glass of milk is 7 rubles.