X=y-3 X+3y=13 so,
first you need to plug in the value of X to make it y-3+3y=13 then you add 3 to both sides and it becomes y+3y=16
After this you can combine the y and 3y to make 4y=16 and you divide both sides by 4 to get y=4
Then you plug 4 in for every time there is a y so, X+3(4)=13 which makes the equation X+12=13 and you subtract 12 from both sides making it X=1
So solution to the system is y=4 and X=1