8. x/y=9/10 (x+y)/y= (9+10)/10=19/10 x/(x+y) =9/19 (y-x)/y=(10-9)/10=1/10 x/(y-x) =9/(10-9) =9/1=9 e) !!!x/y=9/10= (x+9)/(y+10)=9/10 f)!!!! x/y=9/10⇒(x-9)/(y-10)=9/10 exceptand siotuiatia in care x=9 si y=10, cand expresioa nu are sens g) (3x+5y)/y=3x/y+5y/y= =3*9/10 +5*1=27/10+5=77/10 h)(7x-2y)/x= 7-2y/x= 7-2*10/9=7-20/9=(63-20)/9=43/9 7)a0nu inteleg ce vrea  asta ar trebuiswa fiec el mai usor exercitioum, fiind primul darsper sa fi vrutce am scrios mai jos;  practic avem 12/24= 1/2=x/y= 2/4=3/6=4/8=....=n/2n , n∈N* nu se pot scrie toate sunt o infinitate b) analog 30/90=1/3=x/y=2/6=3/9=4/12=....=n/3n c) 18/36=1/2=x/y= ...ca la punctul a)