1)
3x+6y-y=27
4x+4y-3x=23
3x+5y=27
x+4y=23
x=23-4y
3(23-4y)+5y=27
69-12y+5y=27
-7y=27-69=-42
y=6
x=23-4*6=-1
2)
5x-2y=8
12x+18-y=41
5x-2y=8
12x-y=23
y=12x-23
5x-2(12x-23)=8
5x-24x+46=8
-19x=8-46=-38
x=2
y=12*2-23=1
3)
2x+3x+3y=11
7x+21y-6x=-59
5x+3y=11
x+21y=-59
x=-59-21y
5(-59-21y)+3y=11
-295-105y+3y=11
-102y=306
y=-3
x=-59-21*(-3)=-59+63=4