На скамейку сели малыши.Дюймовочка занимает 1 см,Незнайка-6см,а доктор Пилюлькин-8 см.Уместятся ли они, если длина скамейки 2 дм?

1/10 + 3/10=4/10=2/5
7/11+ 1 2/11 = 1 9/11
1/8 + 3/8 = 4/8 = 1/2
1 7/9 - 4/9 = 1 3/9 = 1 1/3
2 - 1/5 = 1 4/5
1 - 5/6=1/6
17/24 - 5/24= 12/24=1/2
1- 2/9=7/9
2 1/5 + 1/5 = 2 2/5
Остальное решили :)))

Просто переварачиваешь
3/10=10/3
4/5=5/4
13/15=15/13
6/25=25/6
21/28=28/21
5/3=3/5
35/44=44/35
200/11=11/200

<span> 
</span><span><span><span><span>   <span><span><span /></span></span><span>1)(1.8+х)*21=71.4
</span><span><span><span><span>((9/5)+x)*21 = 71.4  </span></span><span><span> 9/5+x)*21 = 71.4 </span></span></span></span>     <span><span><span><span> 21*x = 33.6 </span></span></span></span>     <span><span><span><span> x = 33.6 / (21) </span></span></span></span>   <span><span><span><span> x = 1.6 </span></span></span></span></span></span></span></span>   <span><span><span><span>  
<span><span><span><span><span>2)16*(4*x-(17/5)) = 6.08</span></span></span></span></span>   <span><span><span><span> 16*4*x+16*17/5) = 6.08 </span></span></span></span>     <span><span><span><span> 64*x = 60.48 </span></span></span></span>     <span><span><span><span> x = 60.48 / (64) </span></span></span></span>   <span><span><span><span> x = 0.945 </span></span><span><span>   <span><span><span><span><span>3)(x-1.25)*(4.5) = 27</span></span></span></span></span>   <span><span><span><span> (x-1.25)*(9/2) = 27 </span></span></span></span>   <span><span><span><span> x-1.259/2 = 27 </span></span></span></span>     <span><span><span><span> 9*x/2 = 32.625 </span></span></span></span>   <span><span><span /></span></span>   <span><span><span><span> x = 32.625 / (9/2) </span><span><span>     x = 7.25</span></span></span></span></span>     <span><span><span /></span></span>   <span><span><span><span><span>4)(x+19.64)*0.18 = 144</span></span></span></span></span>     <span><span><span><span> x*0.18+19.64*0.18 = 144 </span></span></span></span>       <span><span><span><span> x = 140.4648 / (0.18) </span></span></span></span>   <span><span><span><span> x = 780.36 </span></span><span><span> 5) <span>17 (1,6-5x) = 2.38</span>   <span><span><span><span> 17*(8/5-5*x) = 2.38 </span></span></span></span>     <span><span><span><span> -85*x = -24.82 </span></span></span></span>   <span><span><span><span> Разделим обе части ур-ния на -85 </span></span></span></span>   <span><span><span><span> x = -24.82 / (-85) </span></span></span></span>   <span><span><span><span> x = 0.292 </span></span></span></span><span>6) <span>9,66÷(x+0,17)=23</span></span> 9.66/(х+0.17)=23 9.66=(х+0.17)*23 <span>9.66=23х+3.91,  23х=5.75</span> x = 0.25     </span></span></span></span></span></span><span><span>     </span></span></span></span></span></span></span></span>

*************************************************















****************************************************















****************************************************

Задача

Дано
Прямоугольник АВСД
АВ= (х+12)
ВС= х

Если к АВ прибавить 13 см, то получится (х+12)+13
Если ВС увеличить в 6 раз, получается 6х

Составляем уравнение









 Сторона ВС

По условию задачи сторона АС на 12 см длиннее стороны ВС, получаем

 см - сторона ВС

Ответ: 17 см