The ordered pair (12,-2) is not a solution for the following system of equations.
When substituting 12 is x, and -2 is y
x - y = 14
12 - - 2 = 14
(The negative sign in front of the negative two changes the negative two into a positive two)
12 + 2 = 14
This statement is true.
3(-2) + 2(12) = 21
-6 + 24 = 21
This statement is false.
I hope this helps you :)