(a+c)/(a-c)—(b+d)/(b-d)通分消除同因式后可得2(bc-ad)/(a-c)(b-d),因为a/b=c/d可得ad=bc,所以2(bc-ad)/(a-c)(b-d)=0由此可得a+c/a-c=b+d/b-d
(a-b)/b=a/b-1=3/5所以a/b=3/5+1=8/5
(a+c)/(a-c)—(b+d)/(b-d)通分消除同因式后可得2(bc-ad)/(a-c)(b-d),因为a/b=c/d可得ad=bc,所以2(bc-ad)/(a-c)(b-d)=0由此可得a+c/a-c=b+d/b-d
(a-b)/b=a/b-1=3/5所以a/b=3/5+1=8/5