Let's start by changing the unit of measurement from liters (L) to milliliters (mL), since milliliters is the form in which you are giving your answer. Doing this tells us Lamar drinks 550 mL of milk every day. Since you need to find out how much milk he drinks in 5 days, just multiply the first answer by 5, so 550 x 5. This gives us 2750 mL.
