a+b=6 ===> a=6-b2a+b=0 > 2(6-b)+b=0 ===> 12-b=0 > b=12 > a=6-12=-6
a+b=5 >a=5-b2a-4b=1 > 2(5-b)-4b=1 > 10-6b-1=0 > 6b=9 ===> b=9/6=1.5 ===> a=5-1,5=3,5
a+b=6 ===> a=6-b
2a+b=0 > 2(6-b)+b=0 ===> 12-b=0 > b=12 > a=6-12=-6
a+b=5 >a=5-b
2a-4b=1 > 2(5-b)-4b=1 > 10-6b-1=0 > 6b=9 ===> b=9/6=1.5 ===> a=5-1,5=3,5