1. 330 мин +285 мин = 615 мин
2. 615 мин - 330 мин = 285 мин
3. 84 ч + 136 ч = 220 ч
4. 220 ч - 136 ч = 84 ч
х + ( х +17 ) = 53
2х + 17 = 53
2х =53 - 17
2х = 36
х =36 :2
х =18
проверка :
18 + ( 18 + 17 ) = 53
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