Itzik 45 seconds to fill an 18 down container how long will it take to fill a 40 gallon container

When answering this question, I'm assuming "18 down" means 18 gallons
To find the answer, we can divide:
40/18 = 5
( This basically means that there are 5 containers in the 40 gallon container)
knowing this:
45*5 = 225
(Basically solves the time to fill 5 containers)
It will take 225 seconds

If you assume 18 down means 18 gallons, then you can use a proportion.

(45 sec)/(18 gal) = (x)/(40 gal)

18x = 45 * 40 sec

18x = 1800 sec

x = 100 sec

It takes 100 seconds.