1)(х-3)/(ху-х²)-(3-у)/(ху-у²)=(х-3)/х(у-х)+(3-у)/у(у-х)=(ху-3у+3х-ху)/ху(у-х)=
=-3(у-х)/ху(у-х)=-3/ху
2)[(a+5b)/(a²-5ab)-(a-5b)/(a²+5ab)]*(25b²-a²)/5b²=-4/b
(a+5b)/a(a-5b)-(a-5b)/a(a+5b)=(a²+10ab+25b²-a²+10ab-25b²)/a(a²-25b²)=
=20ab/(a²-25b²)=20b/(a²-25b²)
20b/(a²-25b²)*(25b²-a²)/5b²=-4/b