Answer:
x=2, y=-3
Step-by-step explanation:
x+3y+-7
move variable to the right and -3y from each side
x+3y-3y=-7-3y
x= -7-3y
3x -4y=18
3(-7-3y)-4y=18
solve for y, distribute
-21-9y-4y=18
collect like terms
-21-13y=18
move constant and change sign
-13y=18+21
add
-13y=39
divide by -13
y= -3
substitute
x=-7-3(-3)
solve
x=2
