Discussion 2: Models for Addition and Subtraction 8282 unread replies.8282 replies. For the problems below, (a) classify the word problem (based on the tables from page 21 of the coursepack), (b) create separate drawing for each problem based on the conceptual model that it relates to, and (c) describe how the drawing can be used to find/show the solution. Andria poured herself 12 ounces of milk. She drank 7 ounces. How much milk is left in her glass? Byron is training for a marathon. Today he needs to run 12 miles. He has run 7 miles already. How much farther does Byron need to run today to reach his training goal? Mari is 12 years old and her brother Liu 7 years old. How much older is Mari than Liu?