275*6=1650(т)тракторов за 6 месяцев
320*4=1280(т)тракторов за 4 месяца
6+4=10(м)всего месяцев
1650+1280=2930(т) за все время
ответ: за 10 месяцев выпустили 2930 тракторов.
X=317
a=427
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Х - первое число
2,75х - второе число
1/3(х + 2,75х) - третье число
х + 2,75х + 1/3(х + 2,75х) = 80
х + 2,75х + 1/3х + 2,25х = 80
6х + 1/3х = 80
х(6 + 1/3) = 80
х = 80 : (6 + 1/3)
х =
Не могло потому что учеников 30 ,а судили 31