9 1\4*3 9\13 =37/4*48/13=37/1*12/13=444/13=34.2/3
25-10x-10x+4x^2
(4x^2-10x)-(10x-25)
(2x-5)(2x)-(2x-5)5=
(2x-5)(2x-5)
2x - <span> </span><span>песок</span>
<span>5x - </span><span>чернозеm</span>
<span>2x + 5x = 42</span>
<span>7x = 42</span>
<span>x = 6</span>
<span>
</span>
<span>2 * 6 = 12 - pesok</span>
<span>5 * 6 = 30 - chernozem</span>