Cylinder N and Cylinder P have a total amount of 4644 mℓ of water. For Cylinder P and Cylinder Q, the total amount of water is 4707 mℓ. The amount of water in Cylinder N is ²₅ the amount of water in Cylinder Q. What is the average amount of water in the 3 cylinders?
Cylinder N = 2 u
Cylinder Q = 5 u 

Cylinder P + Cylinder N = 4644 --- (1)
Cylinder P + Cylinder Q = 4707 --- (2)

(2) - (1)
(Cylinder P + Cylinder N) - (Cylinder P + Cylinder Q) = 4707 - 4644
5 u - 2 u = 63
3 u = 63

1 u = 63 ÷ 3 = 21
Cylinder N = 2 u = 21 x 2 = 42

Cylinder N + Cylinder P + Cylinder Q = 42 + 4707 = 4749 mℓ

Average amount of water in the 3 cylinders
= 4749 ÷ 3 
= 1583 mℓ

Answer(s): 1583 mℓ