1/a-1/b=6
(b-a)/ab=6
b-a=6ab
(2a-2b-7ab)分之(a-2ab-b)=[(a-b)-2ab]/[2(a-b)-7ab]
=[-6ab-2ab]/[2*(-6ab)-7ab]
=[-8ab]/[-19ab]
=8/19
1/a-1/b=6
(b-a)/ab=6
b-a=6ab
(2a-2b-7ab)分之(a-2ab-b)=[(a-b)-2ab]/[2(a-b)-7ab]
=[-6ab-2ab]/[2*(-6ab)-7ab]
=[-8ab]/[-19ab]
=8/19