26/24:2=13/12
Всё оч просто!!!
1/4=5/20; 2/5=6/15; 5/6=30/36; 15/20=3/4.
<span>1) итак,вес первой = 24,8кг, </span>
<span>2) вторая = 24,8 + 8,75 = 33,55 </span>
<span>3) третья = 33,55 - 1,9 = 31,65 </span>
<span>4) сумма равна = 24,8 + 33,55 + 31,65 = 90 кг</span>
<span> (x+20)*45=3105</span>
<span>45х + 900 = 3105</span>
<span>45х = 3105-900</span>
<span>45х = 2205</span>
<span>х =2205/45</span>
<span>х=49</span>