3системы 1) x+y=3 3x+1=4y 2) 3x-2y=5 x-y=6 3) x+7y=3 y-3x=6

1)x=3-y
9-3y+1=4y
7y=10
y=10/7
x=3-10/7=11/7
2)x=6+y
3(8+y)-2y=5
24+3y-2y=5
y=5-24
y=-19
x=6-19=-13
3)x=3-7y
y-3(3-7y)=6
y-9+21y=6
22y=15
y=15/22
x=3-105/22=-39/22