2/3y-1/3=5/9; 3/4y-2/3=7/12

2/3у-1/3=5/9                   2/3у=5/9+1/3 2/3у=5/9+3/9 2/3у=8/9 у=8/9:2/3 у=1 1/3 3/4у-2/3=7/12 3/4у=7/12+2/3 3/4у=7/12+8/12 3/4у=15/12 у=15/12:3/4 у=1 2/3 2/3у-1/3=5/9у 2/3у-5/9у=1/3 6/9у-5/9у=1/3 1/9у=1/3 у=1/3:1/9 у=3 3/4у-2/3=7/12у 3/4у-7/12у=2/3 9/12у-7/12у=2/3 2/12у=2/3 у=2/3:2/12 у=4