Answer the following question.
Eliza buys 200 ornamental rings to sell in their local shop, twice the number of the remaining stock. After selling 3/4 of the total stock, her mother buys 300 more ornamental rings, and after three days, sells 150. What's the total number of ornamental rings remaining in the store?
Step-by-step reasoning process: If Eliza restocked twice the original number of ornamental rings, the number was 200 / 2 = 100 rings. The total number of ornamental rings in stock is now 200 + 100 = 300 rings. When she sells 3 / 4 of the stock, the total number of rings sold is 3 / 4 * 300 = 225 rings. The remaining stock is 300 - 225 = 75 rings. When her mother buys 300 more rings, the stock is boosted to 75 + 300 = 375 rings. She then sells out 150, reducing the stock to 375 - 150 = 225 rings.
The answer is 225.

Answer the following question.
Eduardo is a teacher. He taught 3 classes last week while his colleague Frankie taught double what Eduardo teaches. How many classes did Eduardo and Frankie teach in total?
Step-by-step reasoning process: Frankie taught 3 * 2 = 6 classes. Combined, Frankie and Eduardo taught 3 + 6 = 9 classes.
The answer is 9.

Answer the following question.
Trey is hanging wall decorations around his house. He uses a nail for each of two-thirds of them, a thumbtack for each of two-fifths of the rest, and a sticky strip for each of the other decorations. He used 15 sticky strips. How many nails did Trey use?
Step-by-step reasoning process: Trey used 15 sticky strips for 3 / 5 of the remaining decorations after using nails, so he used 15 *  / 3 / 5 = 25 thumbtacks and sticky strips. The 25 decorations were 1 / 3 of the total decorations, so he used 25 / 1 / 3 = 75 total decorations. The nails were 2 / 3 of the decorations, so Trey used 75 decorations * 2 / 3 = 50 nails.
The answer is 50.

Answer the following question.
Patricia has 4 barrels of 7 gallons each. All of them are empty, and there's only one faucet with a flow rate of 3.5 gallons per minute. How many minutes will it take to fill all 4 barrels?

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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Step-by-step reasoning process: If Patricia has 4 barrels and each barrel has 7 gallons, then in total she needs 4 * 7 = 28 gallons. If the faucet can provide 3.5 gallons every minute, then she will need 28 / 3.5 = 8 minutes to fill all 4 barrels.
The answer is 8.