remember that you can do anything to an equaiton as long as you do it to both sides ok so subsitution basiclalyy you subsitute a known thing for an unknown thing so y=3x+3 and y=x-1 they both equal y so 3x+3=y=x-1 3x+3=x-1 subtract x from both sides 2x+3=-1 subtract 3 from bot sides 2x=-4 divide both sides by 2 x=-2 subsitute y=x-1 y=-2-1 y=-3
