How many times can a 40-gallon barrel be filled from 5 casks, each holding 120 gallons?

15 times

Step-by-step explanation:

Each cask holds 120 gallons, so if we have 5 casks, we have a total of 120 * 5 = 600 gallons

We want to know how many times can a 40-gallon barrel can be filled, so we can do a rule of three:

1 barrel -> 40 gallons

X barrels -> 600 gallons

1/X = 40/600

X = 600/40 = 15 barrels

So the barrel can be filled 15 times