25 points I'll give Brainliest if you show your work, including the points that you use to calculate the slope and y-intercept!!! Eric plotted the graph below to show the relationship between the temperature of his city and the number of cups of lemonade he sold daily:

A scatter plot is shown with the title Lemonade Sales. The x-axis is labeled High Temperature, and the y-axis is labeled Cups of Lemonade Sold. Data points are located at 30 and 4, 40 and 6, 40 and 8, 50 and 2, 55 and 10, 65 and 14, 70 and 16, 75 and 14, 85 and 19, 90 and 20.
Part A: Describe the relationship between the temperature of the city and the number of cups of lemonade sold. (I already know this one)
Part B: Describe how you can make the line of best fit. Write the approximate slope and y-intercept of the line of best fit. Show your work, including the points that you use to calculate the slope and y-intercept. (3 points)