Answer:
82 cards to start with
Explanation:
Represent the initial count of cards by c.
After Jason added 4 new cards, he had c + 4 cards.
The dog ate half of these: (c + 4)/2, which came to 43 cards.
Thus, (c + 4)/2 = 43 cards. Solving for c, we get c + 4 = 86, so c = 82 cards.