1,.x-y=1,x+y=2; 2.2x+3y=6,x-2y=5; 3.2x-2y=2,2x+2y=4; 4.2x-y=3,2x+y=8; 5.3x+4y=12,3x+y=9; 6.4x-2y=6,4x+2y=16; 7.9x+12y=36,9x+3y=27; 8.8x-4y=12,8x+4y=32.