14. 20x+3y=-6
-20x+10y=-20
13x=-26
x=-2
20+5y=-10
5y=-30
y=-6
15. 6x+6y=0
-6x+9y=-75
15y=-75
y=-5
6x-30=0
6x=30
x=5
16. -8x-8y=-16
8x+20y=-20
12y=-36
y=-3
-4x+30=10
-4x=-20
x=5
17. 14x-6y=12
-14x+7y=-7
y=5
7x-15=6
7x=21
x=3
18. -10x+15y=60
10x- 6y= 12
9y=72
y=8
10x-48=12
10x=60
x=6
19. 10x+10y=-30
-10x+30y=110
40y=80
y=2
10x+20=-30
10x=-50
x=-5
20. -12x+6y=18
-10x-6y=-18
-22x=0
x=0
0+3y=9
3y=9
y=3
