He wants to run 100 * .2 = 20 miles more than he used to. So he needs to run 100 + 20 = 120 miles. He is doing this in 280 / 7 = 40 weeks. So he needs to add 120 / 40 = 3 miles per week.
The answer: 3
Reverse engineering the question: James injured his ankle and decides to slowly start working back up to his previous running goals and then surpass them. Before the injury, he was able to run 100 miles per week. He wants to get up to 20% more than that total in 280 days and each week he will increase miles walked in the week by the same amount. How many miles does he need to add per week?

Each dog consumes 250 grams x 2 = 500 grams of dog food each day. So, 4 dogs consume 500 grams x 4 = 2000 grams of dog food each day. Since there are 1000 grams in 1 kilogram, then the 4 dogs can consume 2000 / 1000 = 2 kilograms of dog food each day. Aunt Gemma bought a total of 50 kilograms x 2 = 100 kilograms of dog food. Hence, it will last 100 kilograms / 2 kilograms = 50 days.
The answer: 50
Reverse engineering the question: Aunt Gemma has four dogs. She feeds them with dog food twice a day. Each dog can consume 250 grams of food per meal. If aunt Gemma bought 2 sacks of dog food, each weighing 50 kilograms, how many days will those food last?

Each batch serves 6 people, and there are 42 people coming to the party, so she needs to make 42 / 6 = 7 batches. Each batch requires 4 avocados, so she will need 4 * 7 = 28 avocados.
The answer: 28
Reverse engineering the question: Allie's making guacamole for a party. Each batch requires 4 avocados and serves about 6 people. If 42 people are going to be at the party including her, how many avocados does she need?

Let x represent the number of Chevys. Fords:3 + 2x. Buicks:4(3 + 2x) = 12 + 8x. Total:x + 3 + 2x + 12 + 8x = 301. 11x + 15 = 301. 11x = 286. x = 26. Buicks:12 + 8(26) = 220.
The answer: 220
Reverse engineering the question:
Jim collects model cars, and he has 301 models total. Jim has 4 times as many Buicks as Fords, and 3 more than twice the number of Fords than Chevys. How many Buicks does Jim have?