(3-2y)/y²-(y-12)/6y=(18-12y-y+12)/6y=
(30-13y)/6y
20/(a²+5a)-4/a=20/a(a+5)-4/a=(20-4a-20)/a(a+5)=-4a/(a²+5a)
(a-15)/(4a-20)-(a-5)/(4a+20)+30/(a²-25)=
(a-15)/4(a-5)-(a-5)/4(a+5)+30/(a-5)(a+5)=
(a-15)(a+5)-(a-5)²+120)/4(a-5)(a+5)=
(a²+5a-15a-75-a²+10a-25+120)/4(a-5)(a+5)=
20/4(a-5)(a+5)=5/(a²-25)