Предмет: Математика, автор: 123456sasha789

Пальто стоило 180 грн. Сначала оно подорожало на 20 %, а потом подешевело на 20 %. Какой стала цена пальто после этих изменений? На сколько процентов изменилась начальная цена?

Ответы

Автор ответа: avtopilot2

1. Подорожало 20%, то есть 180 + 36 (это 20%) = 216 (грн)
2. Теперь найдём цену после удешевления на 20% и получим
   216 - 43,2 = 172,8 (грн)
3. Узнаем на сколько % изменилась начальная цена. Для этого составим пропорцию:    180 ----- 100%
172,8     ------ Х %
основное правило ПРАВИЛЬНОЙ пропорции: произведение крайних членов равно произведению средних членов пропорции.
Получим: Х = (172,8 х 100) : 180 = 96 (%) столько составляют 172,8
И теперь от 100 - 96 = 4(%)
ответы: 1. Цена стала после изменений 172,8 грн.
    2. На 4% снизилась от первоначальной стоимости.

123456sasha789: а можно как-то попроще? Если не сложно)

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