# Which of the pairs of numbers is the solution to the system of equations x + y = 3 3x-y = 5 (-2, -1) (-1,2) (2,1) (-2,1)

In order to find out which of the pairs of numbers is a solution to a given system of equations, he will substitute these pairs of numbers in the equations of the system and check whether these numbers satisfy the equations.

1) Check the pairs y (-2; -1). Substituting the values x = -2, y = -1 and the 1st equation of the system, we get:

-2 + (-1) = 3;

-3 = 3.

Therefore, this pair of numbers is not a solution to the system of equations.

2) Check the pairs y (-1; 2). Substituting the values x = -1 y = 2 in the 1st equation of the system, we get:

-1 + 2 = 3;

1 = 3.

Therefore, this pair of numbers is not a solution to the system of equations.

3) Check the pair (2; 1). Substituting the values x = 2, y = 1 in the 1st equation of the system, we get:

2 + 1 = 3;

3 = 3.

Substituting the values x = 2, y = 1 into the 2nd equation of the system, we get:

3 * 2 – 1 = 5;

6 – 1 = 5;

5 = 5.

Therefore, this pair of numbers is a solution to a system of equations.

4) Check the pairs y (-2; 1). Substituting the values x = -2 y = 1 in the 1st equation of the system, we get:

-2 + 1 = 3;

-1 = 3.

Therefore, this pair of numbers is not a solution to the system of equations.

Answer: (2; 1).