Решение смотрите на фото.
Х=2/3х+1
х-2/3х=1
3/3х-2/3х=1
1/3х=1
х=1÷1/3
х=1/1×3/1
х=3/1 х=3
х-1/2=3/4х
х-3/4х=1/2
4/4х-3/4х=1/2
1/4х=1/2
х=1/2÷1/4
х=1/2×4/1
х=1/1×2/1
х=2/1 <span> х=2</span>
х-2/3=5/6х
х-5/6х=2/3
6/6х-5/6=2/3
1/6х=2/3
х=2/3÷1/6
х=2/3×6/1
х=2/1×2/1
х=4/1 <span> х=4
</span>
1 4/5у=у+4
1 4/5у-у=4
4/5у=4
у=4÷4/5
у=4/1×5/4
у=1/1×5/1 <span> у=5
</span>
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=1/3×9/1
у=1/1×3/1
у=3/1 <span> у=3
</span>
3/4у-2/3=7/12у
3/4у-7/12у=2/3
9/12у-7/12у=2/3
2/12у=2/3
1/6у=2/3
у=2/3÷1/6
у=2/3×6/1
у=2/1×2/1
у=4/1 <span> у=4</span>
6у-25-617=0
6у-642=0
6у-=642
У=14
Пропорция:
4,2/28 = х/35
х = 4,2*35/28 = 5,25
<span>ответ: 5,25 кг
Удачи!</span>