How do you solve #3x + y = 7# and #3x - y = 5#?
There are 2 obvious methods which can be used in this example, based on the x and y values in the equations.
The two y terms are additive inverses. This means they have the same value, but opposite signs.
When they are ADDED together, they will make 0.
Substitute into A to find the value of y:
The two x-terms are exactly the same. Make the x term the subject.
solve for y: