What we need to do is convert 15 gallons to quarts.
1 gal = 4 quarts
To find how many quarts 15 gallons is, multiply 15 on both sides of the equation above.
1 gal x 15 = 4 quarts x 15
15 gal = 60 quarts
That means Nels need to buy 60 quart bottles :)
