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