<em>х - число</em>
<em>х * 2/7 = 8/49</em>
<span><em>х = 8/49:2/7 = 8/49 * 7/2 = 8/2 * 7/49 =</em><em><u>4/7</u></em></span>
Все: 33, 55, 88, 35, 38, 53, 58, 83, 85
а) 88, 38, 58
б) 55, 35, 85
в) нет таких
60:100*20=0,6*20=12
1800:100*64=18*64=1152
72:100*3,6=0,72*3,6=2,592
3 * а - (40 - 13) = 3
3 * а - 27 = 3
3 * а = 3 + 27
3 * а = 30
а = 30 : 3
а = 10
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3 * 10 - (40 - 13) = 3
30 - 27 = 3
3 = 3