First, isolate yy in the first equation.
color(blue)([1])" "-3x+3y=3[1] −3x+3y=3
color(blue)([2])" "3y=3+3x[2] 3y=3+3x
color(blue)([3])" "y=1+x[3] y=1+x
Now substitute the value of yy in the first equation to yy in the second equation.
color(red)([1])" "-5x+color(blue)(y)=13[1] −5x+y=13
color(red)([2])" "-5x+color(blue)((1+x))=13[2] −5x+(1+x)=13
color(red)([3])" "-4x=12[3] −4x=12
color(red)([4])" "x=-3[4] x=−3
Now that we have the value of xx, we will simply substitute this to the first equation.
color(blue)([4])" "y=1+(-3)[4] y=1+(−3)
color(blue)([5])" "y=-2[5] y=−2