Fred bought 7 new baseball trading cards to add to his collection. The next day his dog ate half of his collection. There are now only 33 cards left.
How many cards did Fred start with ?

His dog ate 1/2 of his collection, this means that there are only 33 left. If I multiply 33x2, I will get 66. Therefore, Fred started with 66 cards.

(If you’re not counting the cards he purchased, then Fred would have 59 cards.)