An avant-garde sushi house sells jellyfish for a certain amount and eel for nine times that amount. If the combined cost of one order each kind of sushi is $200, how much does the eel cost? Give the rationale and then the answer.
Let's think step by step. Let j be the cost of the jellyfish and e be the cost of the eel. We know that j + e = $200 and e = 9j. Substituting the second equation into the first equation, we get j + 9j = $200. Combining like terms, we get 10j = $200. Dividing both sides by 10, we get j = $20. Substituting this value back into e = 9j, we get e = 9 * $20 = $180.. The answer is: 180.

Rachel weighs 75 pounds, 6 pounds less than Jimmy and 15 pounds more than Adam. What is the average weight of the three people, in pounds? Give the rationale and then the answer.
Let's think step by step. Jimmy weighs 75 + 6 = 81 pounds. Adam's weight is 75 - 15 = 60 pounds. In total, the three weigh 75 + 81 + 60 = 216 pounds. The average weight of the three is 216 / 3 = 72 pounds.. The answer is: 72.

Peter carried $500 to the market. He bought 6 kilos of potatoes for $2 per kilo, 9 kilos of tomato for $3 per kilo, 5 kilos of cucumbers for $4 per kilo, and 3 kilos of bananas for $5 per kilo. How much is Peter's remaining money? Give the rationale and then the answer.
Let's think step by step. The price of potatoes is 6 * 2 = $12. The price of tomatoes is 9 * 3 = $27. The price of cucumbers is 5 * 4 = $20. The price of bananas is 3 * 5 = $15. The total price Peter spent is 12 + 27 + 20 + 15 = $74. The amount left with Peter is $500 - $74 = $426.. The answer is: 426.