3){ 15+2x+6y=12x+3y
{ 10x-2y-3y=2+6x-3y
{-10x+3y=-15
{4x-2y=2 |:2
{-10x+3y=-15
{2x-y=1
{y=2x-1
{-10x+3(2x-1)=-15
{y=2x-1
{-4x=-15+3
{y=2x-1
{x=-12/(-4)
{x=3
{y=5
Ответ: (3;5)
4) {35x+10y-11y=12x+6y+2
{33+18x-15y=3x+6y-5y
{23x-7y=2
{15x-16y=-33
{x=(7y+2)/23
{(15*7y+15*2)/23-16y=-33 |*23
{x=(7y+2)/23
{105y+30-368y=-759
{y=-759/(-263)=3
(x=(21+2)/23=1
Ответ: (1;3)