12 13/45-(y-5 17/45)=3 23/45

12 13/45-(у-5 17/45)=3 23/45у-5 17/45=12 13/45-3 23/45у-5 17/45=9 13/45-23/45у-5 17/45=8 35/45у=5 17/45+8 35/45у=13 52/45= 14 7/45