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
the solution is x=-2 y=-3 so
(x,y)
(-2,-3)
