Explanation:
Gabby is an editor. She needs to review a textbook with 398 pages. She plans to review 9 pages each day for the next 31 days. She works out that she will have 279 pages left to review after that. Does that sound about right?
398 - ( 9 * 31) = 119 pages left
No, because Gabby will only have 119 pages left after reading 9 pages a day for 31 days. 279 pages is an overestimate.