Question

Solve the following system of equations by substitution.
2x - y = 6
x + y = 6

Answer 1

x+y=6 so y=6-x using this value for y in the other equation:

2x-(6-x)=6

2x-6+x=6

3x-6=6

3x=12

x=4, and since x+y=6, 4+y=6 so

y=2

So the solution is the point (4,2)

Answer 2

y=-x+6

2x-(-x+6)=6

3x=12

x=4

4+y=6

y=2