5x+15=80-8x
5x+8x=80-15
13x=65
x=65:13
x=5
Ответ:5
____
7(3+c)=33+5c
21+7c=33+5c
7c-5c=33-21
2c=12
c=12:2
c=6
Ответ:6
2098*0+1*(207+0:4567)+728:1=1*207+728=935
<span>16 с + 20=7 с + 74</span>
<span>16с-7с=74-20</span>
<span>9с=54</span>
<span>с=54:9</span>
<span>с=6</span>
<span>Ответ:6</span>
<span>Проверка:</span>
<span>16*6+20=7*6+74</span>
<span>116=116</span>