Cylinder V and Cylinder W have a total amount of 2399 mℓ of water. For Cylinder W and Cylinder X, the total amount of water is 4004 mℓ. The amount of water in Cylinder V is ⁴₇ the amount of water in Cylinder X. What is the average amount of water in the 3 cylinders?
Cylinder V = 4 u
Cylinder X = 7 u 

Cylinder W + Cylinder V = 2399 --- (1)
Cylinder W + Cylinder X = 4004 --- (2)

(2) - (1)
(Cylinder W + Cylinder V) - (Cylinder W + Cylinder X) = 4004 - 2399
7 u - 4 u = 1605
3 u = 1605

1 u = 1605 ÷ 3 = 535
Cylinder V = 4 u = 535 x 4 = 2140

Cylinder V + Cylinder W + Cylinder X = 2140 + 4004 = 6144 mℓ

Average amount of water in the 3 cylinders
= 6144 ÷ 3 
= 2048 mℓ

Answer(s): 2048 mℓ