<span>(6.3-k)*1.2=4.68;
</span>6.3-k=4.68/1.2;
6.3-k=3.9;
k=6.3-3.9;
k=2.4
1) <span>5(2у-9)+6у=4(3у-2)-21
10у-45+6у= 12у-8-21
16у-45=12у-29
16у-12у= 45-29
4у= 16
у= 16:4
у= 4
2)</span><span>5у+7(3-у)=3(5-2у)-6
5у+21-7у=15-6у-6
-2у+21=9-6у
6у-2у=9-21
4у= -12
у= -12:4
у=-3
3)</span><span>7у-4(3у+5)=2-3(4у-9)
7у-12у-20= 2-12у+27
-5у-20= 29-12у
12у-5у= 20+29
7у= 49
у= 49:7
у= 7</span>
5 частей 1кг
6 частей х кг
5:6=1:х
х=6×1:5
х=1,2
1,2 кг <span>сахара потребуется .</span>
<span>10k+2*(7k-2)=5*(4k+3)+3k</span>
<span>10k+14k-4=20k+15+3k</span>
<span>24k-4=23k+15</span>
<span>24k-23k=15+4</span>
<span>k=19;</span>
<span>Проверка:</span>
<span>10*19+2(7*19-2)=5(4*19+3)+3*19</span>
10*19+14*19-4=20*19+15+3*19
24*19-4=23*19+15
452=452.