Answer:
x=8,y=-2/3
Step-by-step explanation:
make x the subject of formula
x=7+3y
substitute into the first equation
4(7+3y)+3y=18
28+12y+3y=18
28+15y=18
15y=18-28
15y=-10
y=-10/15=-2/3
since y=-2/3, substitute y into x=7+3y
x=7+3(-2/3)
x=7-2
x=5
