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? Give me reasons, before answering the question
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. So the final answer is 42.