1) .(y+3)/(4y(y-3) -(y-3)/4y(y+3)=((y+3)²-(y-3)²)/4y(y²-9)=
=(y²+6y+9-y²+6y-9)/4y(y²-9)=12y/4y(y²-9)=3/(y²-9);
2)(a-5)/(5a+25)+(3a+5)/(a²+5a)=(a-5)/5(a+5)+(3a+5)/a(a+5)=
=(a(a-5)+5(3a+5))/5a(a+5)=(a²-5a+15a+25)/5a(a+5)=(a²+10a+25)/5a(a+5)=
=(a+5)²/5a(a+5)=(a+5)/5a.