Benny bought 8 new baseball trading cards to add to his collection. The next day his dog ate half of

Benny bought 8 new baseball trading cards to add to his collection. The next day his dog ate half of his collection. There are now only 47 cards left. How many cards did Benny start with?

Let b be the number of baseball trading cards Benny started with. We have the following events:

1. Benny buys 8 new cards, so we add 8 to get b + 8
2. The dog ate half of his cards the next day, so Benny has (b + 8)/2
3. We're told he has 47 cards left, so we set (b + 8)/2 equal to 47

(b + 8)/2 = 47

Cross multiply:
b + 8 = 47 * 2
b + 8 = 94

Type this equation into the search engine, we get b = 86.