1)x+3y=2 x=2-3y x=2-3y x=2-3y
2x+3y=7 2(2-3y)+3y=7 4-6y+3y=7 -3y=3
x=2-3 x=-1 (-1:-1)
y=-1 y=-1
2)x-y=-10 x=-10+y x=-10+y
2x+3y=15 2(-10+y)+3y=15 -20+2y+3y=15
x=-10+y x=-10+6 x=-4 (-4:6)
5y=35 y=6 y=6
3)x-y=3 x=3+y x=3+y x=3+y
3x+2y=1 3(3+y)+2y=1 9+3y+2y=1 5y=-8
x=3+(-1.6) x=2.4 (2.4:1.6)
y=-1.6 y=-1.6