1. The y-intercept 8 means you start off with $8. The slope 1/4 means how much money you have to pay for the amount of tickets purchased for carnival games.
2. The y-intercept 2 means the number of chapters you started reading and the slope 5/4 means the number of chapters you read per day.
3. The y-intercept 3 means the inital (start) cost of a muffin delivery and the slope 2 means the cost of each muffin delivery for the number of muffins you ordered.
Number 3 on the slope part might be the other way around if I'm wrong :)
The middle between two numbers is the average of those numbers. So we add those two numbers together and divide by two. And the answer is (1 + 6) / 2 = 3.5