color(blue)(y=x+1 2x+color(blue)y=7 2x+color(blue)(x+1)=7 3x+1=7 3x=7-1=6 (we substract 1 on each side ) color(red)x=6/3=color(red)2 (we divide by 3 on each side )
Now that we have color(red)x, we can find color(blue)y : color(blue)y=color(red)x+1=color(red)2+1=color(blue)3