Question 906715
addition/elimination
3x+2y=12
x+y=3
3x+2y=12
-3x-3y=-9
add
-y=3
y=-3
x+y=3
x-3=3
x=6

substitution
3x+2y=12
x+y=3
y=3-x
3x+2(3-x)=12
3x+6-2x=12
x=6
x+y=3
6+y=3
y=-3