2x-[2-(2b-1)x]=a-2
2x-x+(2b-1)x=a-2
(1+2b-1)x=a-2
x=(a-2)/2b
(2b-1)x+3=7-[(2-b)x+3]
(2b-1)x+3=7-(2-b)x-3=4-(2-b)x
[(2b-1)+(2-b)]x=1
x=1/(b+1)
所以a-2=1,2b=b+1
得a=3,b=1
2x-[2-(2b-1)x]=a-2
2x-x+(2b-1)x=a-2
(1+2b-1)x=a-2
x=(a-2)/2b
(2b-1)x+3=7-[(2-b)x+3]
(2b-1)x+3=7-(2-b)x-3=4-(2-b)x
[(2b-1)+(2-b)]x=1
x=1/(b+1)
所以a-2=1,2b=b+1
得a=3,b=1