Answer: The class set up 495 chairs.
Explanation:
Hi, to answer this question, first we have to multiply the number of rows (20) by the number of chairs in each row (25).
Mathematically speaking:
20x25= 500
Since they were 5 chairs short, we have to subtract 5 to the previous result.
500-5 = 495
The class set up 495 chairs.
Feel free to ask for more if needed or if you did not understand something.