Step-by-step explanation:
(1) x+10y=20, x=20,y=2
(2) 6x+y=-18, x=-3,y=-18
(3) 2x-9y=-36, x=-18,y=4
(4) x=-6,y=-15
(5) x=9,y=12
(6) x=-18,y=-3
(7) x=16,y=-6
(8) x=14,y=8
(9) x=-12,y=9
(10) x=-15,y=-6
(11) x=12,y=10
