Answer: 9 songs
Explanation:
From the question, Marcus is picking songs to play during a slideshow and the songs are 3 1/2 minutes long each while the slideshow is 31 1/2 minutes long.
To get the number of songs that will play in the slideshow, we divide the timing of the slideshow by the time each music will play. This will be;
31 1/2 ÷ 3 1/2
Change to improper fraction
= 63/2 ÷ 7/2
= 63/2 × 2/7
= 9
9 songs will play on the slideshow.