How many liters of oil in total were in both containers originally?

Question

There were two containers of oil. There was twice as much oil in the second container as in the first one. After using 13 liters of oil from the first container and 7 liters from the second one, the second container still had 3 times more oil than the first one. How many liters of oil in total were in both containers originally?

Answer 1

c1, c2

(c1)*2=c2

(c1)*2-13 and c2-7

(c2-7)*3=(c1)*2-13

(2x-7)*3=2x-13

6x-21=2x-13

4x=8

x=2

c1=2, c2=4

Answer 2

According to the information we can

Let the first container = x

Let the second container = 2x

After using 13 liters from the first container and 7 liters from the second, the second container still had 3 times as much oil than the first one

Now with removal of oil from both the containers we have

The first container has

x - 13

The second container has

2x - 7

According to information given above

2x - 7 = 3(x - 13)

Now we just solve for x by first following PEMDAS, then combining like terms on both sides of the equation

2x - 7 = 3x - 39

39 - 7 = 3x - 2x

32 = x

The first contained 32 liters originally

The second contained 64 liters originally

We can check this by substituting this value for x in all of our equations.

2x = 2(32) = 64 liters for the second container

And

2x - 7 = 3(x - 13)

2(32) -7 = 3(32 - 13)

64 - 7 = 3(19)

57 = 57

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