Cylinder A and Cylinder B have a total amount of 4036 mℓ of water. For Cylinder B and Cylinder C, the total amount of water is 4492 mℓ. The amount of water in Cylinder A is ⁴₇ the amount of water in Cylinder C. What is the average amount of water in the 3 cylinders?
Cylinder A = 4 u
Cylinder C = 7 u 

Cylinder B + Cylinder A = 4036 --- (1)
Cylinder B + Cylinder C = 4492 --- (2)

(2) - (1)
(Cylinder B + Cylinder A) - (Cylinder B + Cylinder C) = 4492 - 4036
7 u - 4 u = 456
3 u = 456

1 u = 456 ÷ 3 = 152
Cylinder A = 4 u = 152 x 4 = 608

Cylinder A + Cylinder B + Cylinder C = 608 + 4492 = 5100 mℓ

Average amount of water in the 3 cylinders
= 5100 ÷ 3 
= 1700 mℓ

Answer(s): 1700 mℓ