Упростите выражение. Пожалуйста срочно

1)(1/2-1/(а+b)):b/a=(a+b-2)(2(a+b))*a/b=
a(a+b-2)/(2(a+b)b)

2)2/(y-1)-10(y-1):10/(y²-1)-(y+1)/(y-1)=
2/(y-1)-10/(y-1)*(y²-1)/10-(y+1)/(y-1)=
2/(y-1)-(y+1)-(y+1)/(y-1)=
(2-(y²-1)-(y+1))/(y-1)=
(2-y²+1-y-1)/(y-1)=(y²-y+2)/(y-1)