First, in 5 seconds, we know that he drinks 25 mL of slushy. We know this because 1 second is 5 mL, so 5 seconds is 25 mL. So, your graph should be going from the 5 second to 25 mL mark, then the 10 second and 50 mL mark, then the 15 mL and 75 mL mark, and so on.