Question: The age of Gladys is equal to twice the sum of the ages of Billy and Lucas. Billy is 3 times younger than Gladys who is 30 years old now. How old will Lucas be three years from now?
Answer: Billy's age is 30 / 3 = 10 years old. The sum of the ages of Billy and Lucas is 30 / 2 = 15. So, Lucas is 15 - 10 = 5 years old now. Therefore, Lucas will be 5 + 3 = 8 years old three years from now. The answer is 8.

Question: In 3 years, Jayden will be half of Ernesto's age. If Ernesto is 11 years old, how many years old is Jayden now?
Answer: Ernesto = 11 + 3 = 14. Jayden = 14 / 2 = 7 in 3 years. Now = 7 - 3 = 4. Jayden is 4 years old. The answer is 4.

Question: Tameka is selling boxes of crackers for her scout troop. On Friday, she sold 40 boxes. On Saturday, she sold 10 fewer than twice that number. And on Sunday, she sold half as many as Sunday. How many boxes did she sell over the three days?
Answer: Saturday's total was 2 * 40 - 10 = 70. Sunday's was 70 / 2 = 35. The sum is 40 + 70 + 35 = 145. The answer is 145.

Question: A father and a son start approaching each other at the same time from opposite ends of a hallway that is 16m long. If the father is walking three times as fast as the son, at what distance from the father's end of the hallway will they meet?
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
Since the father is walking 3 times as fast as his son, their speeds are in a ratio of 3:1 respectively. They started at the same time so they will cover distance at the same ratio of 3:1. Each portion of the distance they covered is 16 / (3 + 1) = 4m. The father covered three portions of the distance which is 3 * 4m = 12m from his end. The answer is 12.