3+((17-3)*2=31 человек. Ещё на всякий случай пересчитай.
1)
Х+7х=864
8х=864
Х=864:8
Х=108(м)- во втором рулоне
2)108*7=756(м)- в первом рулоне
Ответ: в первом рулоне было756метров пленки, во втором-108 метров плёнки.
А(567 + 7843 =8410
2415 - 7843 = 10258
б) 88942 - 44701 =44241
88942 -17942 =71000
в)(830+243)-647=399
(1712+805)-647=1870
30x+165=285
30x=285-165
30x=120
x=120/30
x=4
<span>-7+..3.= -4 </span>
<span><span>-7+(-3)= -10</span></span>
<span><span><span>7+(-3)=4</span></span></span>
<span><span><span><span>(-9)+8=-1</span></span></span></span>
<span><span><span><span><span>(-9)+(-8) = -17</span></span></span></span></span>
<span><span><span><span><span><span>9+(-8)=1</span></span></span></span></span></span>
<span><span><span><span><span><span><span>9+(-9)=0</span></span></span></span></span></span></span>
<span><span><span><span><span><span><span><span>(-11)+11=0</span></span></span></span></span></span></span></span>
<span><span><span><span><span><span><span><span><span>-12+12=0 </span></span></span></span></span></span></span></span></span>