12 13/45-(у-5 17/45)=3 23/45
12 13/45-(у-5 17/45)=3 23/45(у-5 17/45) = 12 13/45-3 23/45 (у-5 17/45) = 8 35/45 у = 5 17/45 + 8 35/45 у = 14 7/45