subsitution
minus 3y from both sides in the first equatio
x=15-3y
subsitute 15-3y for x in other equation
4(15-3y)+2y=30
60-12y+2y=30
60-10y=30
minus 60 both sides
-10y=-30
divide both sides by -10
y=3
sub back
x=15-3y
x=15-3(3)
x=15-9
x=6
(x,y)
(6,3)