<span>(2,61-4х):0,03+4,6=90</span>
<span>2,61-4х : 0,03 = 90 - 4,6</span>
<span>2,61-4х : 0,03 = 85,4</span>
<span>2,61-4х = 85,4 * 0,03 </span>
<span>2,61-4х = <span>2,562</span></span>
<span><span>4х = 2,61 - 2,562</span></span>
<span><span>4х = <span>0,048</span></span></span>
<span><span><span>х = 0,048 : 4</span></span></span>
<span><span><span>х = 0,012</span></span></span>