{3x-y=10
{x/3-y+1/5=1
{y=3x-10
{x/3+((y+1)/5)=1
x/3+(3x-10+1)/5=1
5x+3(3x-9)=15
5x+9x-27=15
14x=42
x=3; y=-1
Ответ:x=3; y=-1