80.5 -( y - 9 3/4 ) =28 5/6

у-9 3/4=80 5/10-28 5/6у-9 3/4=80 15/30-28 25/30у-9 3/4= 79 45/30-28 25/30у-9 3/4=51 20/30=51 2/3у=51 2/3-9 3/4у=51 8/12-9 12/12у=51 8/12-10у=41 8/12=41 2/3