If all questions were 2-pointers, the test would be worth 60 points.
The test's total points are 120.
To find how much the short answers are worth, subtract.
120-60=60. There are 60 points available for short answer.
Each 5-point question adds 3 points to the worth of the test, so divide.
60/3=20.
There are 20 short-answer questions on the test.