The image below shows proof that the point-slope equation is the correct equation in point-slope form that the line passes through the points (7, 5) and (-4, -1)
You can get 3 refills. First you subtract $4.50-$1.65 which equals $2.85. Then you find out how many times 95¢ can go into that. It goes in 3 times so you can get 3 refills.