<span>(4.9+3.5x)(7x-2.8)=0
4.9+3.5x=0 7x-2.8=0
3.5x=-4.9 7x=2.8
x=-1.4 x=0.4</span>
Х + 397 = 1000 - 603 х+605=1000-385
х + 397 = 397 х+605=615
х=397-397 х=615-605
х=0 х=10
1000-х=402+596 218+х=100+248
1000-х=998 218+х=348
х=1000-998 х=348-218
х=2 х=130
3/8х + 25 = 100
3/8х = 100 - 25
3/8х = 75
х = 75 : 3/8
х = 75/1 * 8/3
х = 25 * 8
<u>х = 200 </u>
3/8 * 200 + 25 = 100
600/8 + 25 = 100
75 + 25 = 100
100 = 100