15 6/13-(6 8/3+7 9/13)=201/13-(26/3+100/13)=201/13-638/39=-35/39
<span> 6Х-3Х=522</span>
<span>3х=522</span>
<span>х=522:3</span>
<span>х= 174</span>
<span>
</span>
<span>проверка</span>
<span>6*174-3*174= 522</span>
<span>1044-522= 522</span>
<span>522 = 522</span>
Надо ставить на 4:00 . т.к. между 10:00 и 4:00 не пройдёт 24 часов