Предмет: Математика, автор: andreysamorodow69

Легкая задачка по фото 40 баллов

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Автор ответа: iramazurk

Пошаговое объяснение:

1 цистерна = х т топлива

2 цистерна = у т топлива

Когда взяли из 1 цистерны 2/5 т топлива, то получили : х - 2/5х = 3/5х т топлива

Когда взяли из 2 цистерны 5/8 т топлива, то получили: у - 5/8у = 3/8у т топлива

Составим систему уравнений:

х + у = 858

3/5х = 3/8у

х + у = 858

3/5х - 3/8у = 0 | * 40

х + у = 858

120/5х - 120/8у = 0

х = 858 - у

24х - 15у = 0

24(858 - у) - 15у = 0

20592 - 24у - 15у = 0

-39у = -20592

у = -20592 : (-39)

у = 528

х = 858 - у

х = 858 - 528

х = 330

1 цистерна = (х) = 330 т топлива

2 цистерна = (у) = 528 т топлива

Автор ответа: nepustilipoeta

пусть в первой цистерне х л топлива, тогда во второй (858-х) л,

когда из первой цистерны использовали 2х/5, осталось

х-2х/5=5х/5-2х/5=3х/5 (л);

а из второй использовали (5/8)*(858-х) литра, осталось

(858-х)-(5/8)(858-х)=(3/8)(858-х)=321.75-(3х/8)

т.к. осталось поровну, то получим такое уравнение

3х/5=321.75-(3х/8)

умножим обе части на 40 получим

8*3х=12870-3*5х

24х+15х=12870

39х=12870

х=12870/39

х=330

значит, в первой цистерне было первоначально 330 л, тогда во второй цистерне 858-330=528(л)

Отвте 330л; 528л

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