To determine the total number of MP3s Sam has by the end of the week, we need to add the number of MP3s he started with to the number of MP3s he downloaded during the week.
Sam started with 88 MP3s on his MP3 player. He then downloaded an additional 22 MP3s throughout the week.
To find the total number of MP3s, we can add these two numbers together:
88 + 22 = 110
Therefore, by the end of the week, Sam will have a total of 110 MP3s on his MP3 player.