x-1=2+3y; 5x-7=y+9
x=3y+3; 5(3y+3)-7=y+9
x=3y+3; 15y+15-7=y+9
x=3y+3; 15y+8=y+9
x=3y+3; 15y-y=9-8
x=3y+3; 14y=1
y=1/14; x=3*1/14+3
y=1/14; x=3/14+42/14
y=1/14; x=45/14
ответ: (45/14; 1/14)
::::::::::::::::решение::::::::::::::
x-1=2+3y; 5x-7=y+9
x=3y+3; 5(3y+3)-7=y+9
x=3y+3; 15y+15-7=y+9
x=3y+3; 15y+8=y+9
x=3y+3; 15y-y=9-8
x=3y+3; 14y=1
y=1/14; x=3*1/14+3
y=1/14; x=3/14+42/14
y=1/14; x=45/14
ответ: (45/14; 1/14)
::::::::::::::::решение::::::::::::::