Melany has to fence a 5000 feet square field with wire mesh. If one foot of wire mesh is sold at $30, and she had $120000, how many feet of the field will not be fenced? Give the rationale and then the answer.
Let's think step by step. Since one - foot wire mesh is sold at $30, with $120000, Melany can buy $120000 / $30 = 4000 feet of wire mesh. If Melany has to fence 5000 feet of the field and has 4000 feet of wire mesh, she will not fence 5000 - 4000 = 1000 feet of the field.. The answer is: 1000.

Paul is working at a university. He is part of a big project, which involves 70 scientists in total. Half of them are from Europe and one-fifth are from Canada. The rest are from the USA. How many scientists in this project are from the USA? Give the rationale and then the answer.
Let's think step by step. Of all the scientists taking part in the project, half of them are from Europe, which means 70 * 0.5 = 35 people. The number of researchers from Canada is 70 * 1 / 5 = 14 people. That means there are 70 - 35 - 14 = 21 researchers from the USA.. The answer is: 21.

John has just turned 39. 3 years ago, he was twice as old as James will be in 6 years. If James' older brother is 4 years older than James, how old is James' older brother? Give the rationale and then the answer.

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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Let's think step by step. John was 39 - 3 = 36 years old 3 years ago. So that means in 6 years James will be 36 / 2 = 18 years old. So right now James is 18 - 6 = 12 years old. So James's older brother is 12 + 4 = 16 years old.. The answer is: 16.