Вопрос школьника по предмету Математика
В коробке лежали карандаши.Сначала из неё взяли 50% карандашей, а затем 40% остатка.После этого в коробке осталось 9 карандашей.Сколько карандашей было в коробке первоначально
Ответ учителя по предмету Математика
9 карандашей — 40%
х карандашей — 100%
900=40х
х=900/40=90/4=22,5
теперь 22,5 — 50%
х -100%
х=45
ответ: первоначально в коробке было 45 карандашей
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