Question: I would love to understand how to solve this problem: Olivia uploaded 72 pictures to Facebook.  She put the same number of the pics into 8 albums.  3 of the albums were selfies only and 2 of the albums were portraits.  How many portraits and selfies did she have?
Can you explain?
Answer: 
Olivia had 72 pictures / 8 albums = 9 picture per album.
Olivia had 3 selfie albums * 9 pictures = 27 pictures.
Olivia had 2 portrait albums * 9 pictures = 18 pictures.
The total of portraits and selfies for Olivia is 27 + 18 = 45 pictures.