so elimination lets say x+y=10 x+2y=15 if we make the first equation negative and add it to the second we get -x+x-y+2y=-10+15 or (x cancels out) y=5
subsitution
x+3y=7 y=x+1 subsitute y=x+1 for y in the first equation x+3(x+1)=7 distribute x+3x+3=7 group like terms 4x+3=7 subtract 3 from both sides 4x=4 divide both sides by 4 x=1 subsitute x=1 into second equation (y=x+1) y=(1)+1 y=2
