Cylinder R and Cylinder S have a total amount of 2545 mℓ of water. For Cylinder S and Cylinder T, the total amount of water is 3765 mℓ. The amount of water in Cylinder R is ³₇ the amount of water in Cylinder T. What is the average amount of water in the 3 cylinders?
Cylinder R = 3 u
Cylinder T = 7 u 

Cylinder S + Cylinder R = 2545 --- (1)
Cylinder S + Cylinder T = 3765 --- (2)

(2) - (1)
(Cylinder S + Cylinder R) - (Cylinder S + Cylinder T) = 3765 - 2545
7 u - 3 u = 1220
4 u = 1220

1 u = 1220 ÷ 4 = 305
Cylinder R = 3 u = 305 x 3 = 915

Cylinder R + Cylinder S + Cylinder T = 915 + 3765 = 4680 mℓ

Average amount of water in the 3 cylinders
= 4680 ÷ 3 
= 1560 mℓ

Answer(s): 1560 mℓ