Reasoning and answer: On day 2 Kim trades 6 earrings because 3 x 2 = 6. On day 3 Kim trades 5 earrings because 6 - 1 = 5. In total she trades 14 pairs of earrings because 3 + 6 + 5 = 14. She trades these for 126 gum - balls because 14 x 9 = 126. These last her 42 days because 126 / 3 = 42.
The answer: 42
What was the question?
Question: Kimberly loves gumballs and will trade almost anything she owns for them. A friend knows that Kim has a bunch of shiny new earrings that she loves. She agrees to give Kim 9 gumballs for each pair of earrings. On the first day, Kim brings her 3 pairs of earrings. On the second she brings her twice as many. On the third day, she brings 1 less than she brought on the second day. If Kim eats 3 gumballs a day, how many days will the gumballs last?

Reasoning and answer: Twenty bottles of oil is equal to 200 mL x 20 = 4000 mL. Since 1 liter is equal to 1000 mL, then the store owner had 4000 / 1000 = 4 liters of oil.
The answer: 4
What was the question?
Question: A store owner repacked his oils into 200 mL bottles. He was able to make 20 bottles. How many liters of oil did the store owner have?

Reasoning and answer: She spent $60 on her younger sister because 4 x 15 = 60. She buys 3 lego sets for her older sister because 60 / 20 = 3.
The answer: 3
What was the question?
Question:
Tonya is buying Christmas gifts for her sisters. She has 2 sisters and wants to spend the exact same amount on each. She buys her younger sister 4 dolls that cost $15 each. She plans to buy lego sets for her older sister. They cost $20 each. How many lego sets does she buy?