Cylinder N and Cylinder P have a total amount of 3266 mℓ of water. For Cylinder P and Cylinder Q, the total amount of water is 3800 mℓ. The amount of water in Cylinder N is ⁴₇ the amount of water in Cylinder Q. What is the average amount of water in the 3 cylinders?
Cylinder N = 4 u
Cylinder Q = 7 u 

Cylinder P + Cylinder N = 3266 --- (1)
Cylinder P + Cylinder Q = 3800 --- (2)

(2) - (1)
(Cylinder P + Cylinder N) - (Cylinder P + Cylinder Q) = 3800 - 3266
7 u - 4 u = 534
3 u = 534

1 u = 534 ÷ 3 = 178
Cylinder N = 4 u = 178 x 4 = 712

Cylinder N + Cylinder P + Cylinder Q = 712 + 3800 = 4512 mℓ

Average amount of water in the 3 cylinders
= 4512 ÷ 3 
= 1504 mℓ

Answer(s): 1504 mℓ