( 16÷1 1/3 - 4 5/9 + 2 3/4 : 11 + 3 1/4) : (( 7 1/3 - 6 5/9) * 5/28) = 36
1)16÷11/3=26*3/11=78/11=7 1/11
2)2 3/4÷11=11/4÷11=11/4*1/11=1/4
3)7 1/11-4 5/9=7 9/99 - 4 55/99=6 108/99- 4 55/99=3 53/99
4)2 53/99+2 3/4=4 509/396=5 113/396
5)7 1/3-6 5/9=
7 3/9-6 5/9=6 12/9-6 5/9=7/9
6)7/9*5/28=5/36
7)5 113/396÷5/36=1980/396÷5/36=1980/396*36/5=396/11=36
<span><u>х+у</u>=3 выразим отсюда х.</span>
<span> у</span>
<span>х+у=3у => х=3у-у=2у х=2у</span>
<span>
</span>
<u><span>5х-3у</span></u><span> = <u> 5*2у-3у </u> = <u>10у-3у </u> =<u> 7у </u> = 3,5</span>
<span> х 2у 2у 2у</span>
<span>
</span>
729 : (с - 15) = 81
729 : (c - 15) = 81 , c = (зачеркнутое)15
729/c-15 = 81
729 = 81(c - 15)
9 = c - 15
- c = - 15 - 9
- c = - 24
c = 24 , c =(зачеркнутое равно) 15
с = 24
Ответ: с = 24