[Question]Aubriella is pouring water into a 50-gallon fish tank at the rate of 1 gallon every 20 seconds. How many more gallons will she have to pour into the tank to fill the tank if she poured water into the fish tank for 6 minutes?
[Answer]When she poured water into the gallon for 6 minutes, the total time in seconds she took is 6 minutes * 60 seconds / minute = 360 seconds. If in 20 seconds she poured 1 gallon of water into the tank, in 360 seconds, she poured 360 seconds / 20 seconds / gallon = 18 gallons of water into the tank. Aubriella will have to pour 50 gallons - 18 gallons = 32 more gallons into the tank to fill the tank. The answer is 32.

[Question]Jimmy and Tonya both like collecting matchbooks and stamps. Tonya and Jimmy decide to trade some stamps and matchbooks. They have each decided that one stamp is worth 12 matches. Each matchbook contains 24 matches. If Tonya arrives with 13 stamps, Jimmy has 5 matchbooks, and Jimmy trades all his matchbooks for stamps, how many stamps does Tonya have left?
[Answer]Jimmy has 120 matches because 5 times 24 equals 120. Jimmy trades this for 10 stamps because 120 divided by 12 equals 10. Tonya has 3 stamps left because 13 minus 10 equals 3. The answer is 3.

[Question]Léa bought one book for $16, three binders for $2 and six notebooks for $1. Calculate the total cost of her purchases.
[Answer]The binders cost 3 binders * $2 / binder = $6. The notebooks cost 6 notebooks * $1 / notebook = $6. The amount of Lea’s purchases is: $16 + $6 + $6 = $28. The answer is 28.

[Question]Ben's new car cost twice as much as his old car. He sold his old car for $1800 and used that to pay off some of the cost of his new car. He still owes another $2000 on his new car. How much did his old car cost, in dollars?
[Answer]
His new car costs 1800 + 2000 = 3800 dollars. His old car cost 3800 / 2 = 1900 dollars. The answer is 1900.