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?

There are 96 liters of oil in both containers originally

Step-by-step explanation:

* Lets change the story problem to mathematics equation

- Let the first container had A liters of oil and the second container

 had B liters of oil

- The quantity of oil B in the second container is twice the quantity

  of oil in A in the first container

∴ B = 2A ⇒ (1)

- After using 13 liters from the quantity of oil A in the first container,

 the container had (A - 13) liters

- After using 7 liters from the quantity of oil B in the second container,

 the container had (B - 7) liters

-  After that the quantity of oil in the second container is 3 times

 more oil than the first one

∴ B - 7 = 3(A - 13) ⇒ simplify

∴ B - 7 = 3A - 39 ⇒ add 7 and subtract 3A from both sides

∴ B - 3A = -39 + 7

∴ B - 3A = -32 ⇒ (2)

- Substitute the value of B from (1) into (2)

∴ 2A - 3A = -32

∴ -A = -32 ⇒ × -1

∴ A = 32 liters

- Find the value of B by substitute value of A in (1)

∴ B = 2(32) = 64 liters

- Now find the total liters of oil in both containers

∴ A + B = 32 + 64 = 96 liters

* There are 96 liters of oil in both containers originally

$5.41

step-by-step explanation:

$20 - $14.51 = $5.49.