It costs $10 to go to Pete's Pottery Place to paint custom bowls at a cost of $3.50 per bowl. Janelle plans to paint bowls 5 days this month and then paint b bowls on each day so she can sell them at a craft fair. Which equation represents Janelle's total cost c for the month?

I color coded everything so you can explain in your own words what I did. Everything is labeled.
Part A. Used the points to find the lines I needed using slope formula and formed the y=mx+b form of the line. Then I used the inequality that helped me to include only B and F.
Part B. Used my inequalities and used points B and F to see if the inequalities were true. If true then they work as solutions, if false then they do not. Yours are true, they are solutions.
Part C. Drew the line in green so you could see it and verify the houses. You could also use the line equation and plug in every point house letter and if they are true they are a house John is interested in, if false then that house he is not interested in. I used graphing the line to show you better how to solve.