Answer:
There are 96 liters of oil in both containers originally
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