Answer:
120 papers
Explanation:
Step 1: Determine how many papers has Mrs. Bennett already graded:
Since Mrs. Bennett graded 20% of her students' 150 papers, we can determine how many papers she has already graded by multiplying 0.20 (20% as a decimal) by 150:
Amount of papers graded = 0.20 * 150
Amount of papers graded = 30
Thus, Mrs. Bennet has already graded 30 papers.
Step 2: Subtract 30 from 150 to determine the amount of ungraded papers:
Now we can determine how many papers Mrs. Bennett still must grade by subtracting 30 (20% of 150) from 150:
Amount of papers ungraded = 150 - 30
Amount of papers ungraded = 120
Thus, Mrs. Bennet needs to finish grading 120 papers.