<span>1) 4,8 : 1,5 = 1,8 : 1/8х</span>
<span>домножим обе части на x:
</span>
<span>(4,8 : 1,5) * x = 1,8 : 1/8</span>
<span>x = (1,8 : 1/8) / (<span>4,8 : 1,5</span>) = 8*1,8*1,5/4,8 = 4,5</span>
<span>
</span>
<span><span>2) 13/3 : (2x)= 13/10 : 3</span></span>
<span><span>действуем аналогично:
</span></span>
<span><span><span><span>13/3 : 2</span></span> = (<span><span>13/10 : 3</span></span>) * <span>x</span></span></span>
<span><span><span>x</span> = (<span><span><span><span>13/3 : 2</span></span></span></span>) / <span><span>(<span><span>13/10 : 3</span></span>)</span></span> = 13/6 : 13/30 = (13*30) / (6*13) = 30/6 = 5</span></span>
<span><span>
</span></span>
<span><span><span>3) 3(y-5) - 2(y-4)=8
</span></span></span>
<span><span><span><span><span><span>раскроем скобки</span></span></span>: 3y -15 -2y +8 = 8</span></span></span>
<span><span><span>перенесём числа в правую часть: 3y -2y = 8+15-8
</span></span></span>
<span><span><span>y = 15
</span></span></span>