First find the total number of blueberries Mason has: 200 blueberries / carton * 3 cartons = 600 blueberries. Then divide the total number of blueberries by the number of blueberries per muffin: 600 blueberries / 10 blueberries / muffin = 60 muffins. Then add that number of muffins to the number of cinnamon muffins to find the total number of muffins: 60 muffins + 60 muffins = 120 muffins. Then divide the number of blueberry muffins by the total number of muffins and multiply by 100% to express the answer as a percentage: 60 muffins / 120 muffins * 100% = 50%.
The answer: 50
Reverse engineering the question: Mason has 3 cartons of 200 blueberries. He makes as many muffins as he can with 10 blueberries per muffin. Then he makes 60 cinnamon muffins. What percentage of all the muffins he made have blueberries?

Red:14 crayons. Blue:5 + 14 = 19 crayons. Yellow:19(2) - 6 = 32 crayons.
The answer: 32
Reverse engineering the question: There are 14 red crayons, 5 more blue crayons than red crayons, and 6 less yellow crayons than double the blue crayons. How many yellow crayons are there?

First Jamie wants to figure out how many calories his father needs to lose from 5 pounds x 3500 calories each = 17,500 calories to burn off. Then Jamie needs to figure out how many calories his father will burn per day if he burns 2500 calories - eating 2000 calories = burning 500 calories a day. If Jamie's father wants to burn off 17,500 calories total at 500 calories a day, 17,500 / 500 = 35 days to burn off 5 pounds.
The answer: 35
Reverse engineering the question: Jamie's father gained 5 pounds over the holidays that he wants to lose so his pants will not be as snug. He asks Jamie to help him keep track of his calories. Jamie's father burns 2,500 calories of fat a day by doing light exercise. There are 3,500 calories in a pound of body fat. How many days will it take for Jamie's father to burn off 5 pounds if he does light exercise and sticks to eating 2000 calories a day?

If Rachel and Leah have the same age, then the sum of their ages would be 34 - 4 = 30. So Leah would be 30 / 2 = 15 years old. Hence, Rachel is 15 + 4 = 19 years old.
The answer: 19
Reverse engineering the question:

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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Rachel is 4 years older than Leah. If the sum of their ages is 34, how old is Rachel?