What did I do wrong?
I did the check but I didn’t get the same answer.

Solution = ( 0, 4 )

Step-by-step explanation:

You made one tiny error. When you were attempting to substitute your y value, 4, to derive the x - value, you took the second equation. However, that second equation was x + 2y = 8, when you substituted y as 4 you rewrote this equation as x + 2( 4 ) = 12, instead it should have been x + 2( 4 ) = 8!

If you would like, let me explain how to get the right answer;

And as for your " check " let us substitute these values into both the equations, for true confirmation;

true !

step-by-step explanation:

.there can be infinite values of m and n that can satisfy the above equation. for each value of m of m or n. there maybe infinite sets of solution for the above

step-by-step explanation: