Come up with a question and reasoning that would justify [42] as the answer.
The question is: Wilma has a garden with 3 types of flowers. The garden has 6 rows, with 13 flowers in each row. Wilma has 12 yellow flowers, two times more green flowers, and the rest consist of red flowers. How many red flowers does Wilma have?
Reasoning: The garden has space for 6 * 13 = 78 flowers in total. Wilma has two times more green flowers than yellow flowers, which means she has 2 * 12 = 24 green flowers. That leaves us with 78 - 24 - 12 = 42 red flowers in the garden.

Come up with a question and reasoning that would justify [20] as the answer.
The question is: In ten years, I'll be twice my brother's age. The sum of our ages will then be 45 years old. How old am I now?
Reasoning: Let X be my age now. In ten years, I'll be X + 10 years old. In ten years, my brother will be (X + 10) * 1 / 2 years old. In ten years, (X + 10) + (X + 10) * 1 / 2 = 45. So (X + 10) * 3 / 2 = 45. X + 10 = 45 * 2 / 3 = 30. X = 30 - 10 = 20 years old.

Come up with a question and reasoning that would justify [400] as the answer.
The question is: Jack is stranded on a desert island. He wants some salt to season his fish. He collects 2 liters of seawater in an old bucket. If the water is 20% salt, how many ml of salt will Jack get when all the water evaporates?
Reasoning: First find how many liters of the seawater are salt: 2 liters * 20% = .4 liters. Then multiply that amount by 1000 ml / liter to find the number of ml of salt Jack gets: .4 liters * 1000 ml / liter = 400 ml.