[Question]Mr. Grey's house was worth $100,000. He sold the house to Mr. Brown at a profit of 10%. After one year, Mr. Brown sold the house to his other friend with a 10% loss. How much was Mr. Brown's selling price?
[Answer]Mr. Grey had a $100 000 x 10 / 100 = $10,000 profit. So, Mr. Grey sold the house to Mr. Brown for $100 000 + $10 000 = $110,000. Mr. Brown sold the house $110 000 x 10 / 100 = $11,000 less than its purchased price. Thus, Mr. Brown sold it for $110 000 - $11 000 = $99,000 to his friend. The answer is 99000.
Q: Three towns, Toadon, Gordonia, and Lake Bright, have 80000 people. Gordonia has 1/2 times the total population in the three cities. If the population of Toadon is 60 percent of Gordonia's population, how many people live in Lake Bright?
A: The population of Gordonia is 1 / 2 * 80000 people = 40000 people. Toadon has 60 / 100 * 40000 people = 24000 people. The total population of Gordonia and Toadon is 40000 people + 24000 people = 64000 people. The population of Lake Bright is 80000 people - 64000 people = 16000 people. The answer is 16000.
Question: Camille saw 3 cardinals and four times as many robins as cardinals while bird watching. She also saw twice as many blue jays as cardinals and 1 more than three times as many sparrows as cardinals. How many birds did Camille see?
Answer: Camille saw 3 x 4 = 12 robins. She also saw 3 x 2 = 6 blue jays. Triple the number of cardinals is 3 x 3 = 9. So, she saw 9 + 1 = 10 sparrows. Therefore, Camille saw 3 + 12 + 6 + 10 = 31 birds. The answer is 31.
[Question]The running time of Beast of War: Armoured Command is 10 minutes longer than that of Alpha Epsilon, which is 30 minutes shorter than that of Millennium. If Millennium runs for 2 hours, what is the running time of Beast of War: Armoured Command in minutes?
[Answer]One hour contains 60 minutes so 2 hours contain 60 * 2 = 120 minutes. Alpha Epsilon's running time is 30 minutes less than that of Millennium (which runs for 120 minutes) hence 120 - 30 = 90 minutes. Beast of War: Armoured Command runs for 10 minutes more than Alpha Epsilon hence 90 + 10 = 100 minutes. The answer is 100.
Q: Tom decided to go on a trip. During this trip, he needs to cross a lake, which in one direction takes 4 hours. During this time, Tom needs an assistant to help him with the crossing. Hiring an assistant costs $10 per hour. How much would Tom have to pay for help with crossing the lake back and forth?
A: Crossing the lake two times (back and forth) would take 4 * 2 = 8 hours. So Tom would need to pay an assistant 8 * 10 = $80. The answer is 80.
Question: A fruit and vegetable merchant installed 15 kg of carrots, 13 kg of zucchini and 8 kg of broccoli. He sold only half of them. What mass of vegetables did he sell?
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.
user
You first need to know the total weight of the vegetables, so you add each quantity: 15 + 13 + 8 = 36 kg. Then you have to find half of 36: 36 / 2 = 18 kg. So, he sold 18 kg of vegetables. The answer is 18.