yMnIk20150 -у+3у-у=6-10-8
у=-12

-9х+5х+3х=5-5+3
-х=3
х=-3

10 - y + 3y + 8 = 6 + y
18 + 2y = 6 + y
2y - y = 6 - 18
y = -12
Второе
5- 9х - 3 + 5х = 5 - 3х
2 - 4у = 5 - 3х
-4у +3н = 5 - 2
-у = 3
у = -3