1)
{0,2к=13
{к+m= -9
{k= -9-m
{0,2(-9-m)=13
{-1,8-0,2m=13
{0,2m= -13-1,8
{0,2m=-14,8
{m=74
{k=-83
2)
{x=3
{17x-y=11
{51-y=11
{y=40
3)
{a=6
{2a-b=12
{12-b=12
{b=0
4)
{10х+2у=81
{у=-2,5х
{10х+2(-2,5х)=81
{10х-5х=81
{5х=81
{х=16,2
{у=13,7
5)
{-z-2v+2=5
{z=-7-v
{7+v-2v+2=5
{-v=-4
{v=4
{z=-11