240:а=480:80
240:а=6
а =240 : 6
а =40
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а×(288-190)=392
а×98=392
а =392 : 98
а = 4
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Х × 81 + 67 =553
Х × 81=553-67
Х×81 =486
Х= 486 :81
Х = 6
__________________
489 + с × 5 =9614
с × 5 =9614 - 489
с × 5 =9125
с =9125 : 5
с =1925