Вопрос школьника по предмету Математика
(надо решить задачу уравнением) У меня есть 50 бумажек по 10 и 20 рублей. Всего у меня 650 рублей. Сколько у меня бумажек по 10 рублей и по 20 рублей ?
Ответ учителя по предмету Математика
х -по 10 рублей
у- по 20 рублей
всего 50 купюр ,значит
{х+у=50
(10х+20у=650 разделим на 10
{x+y=50
{x+2y=65 вычтем из (2) первое (1)
2у-у=65-50
у=15 подставим в первое уравнение
х+у=50
х+15=50
х=35
Ответ : 15 купюр по 20 рублей и 35 купюр по 10 рублей.
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-16-1,2y=40,1+3,9y
Ответ:y=?