Question

You bought 12 baseball cards on Monday and 24 baseball cards on Tuesday. After giving some baseball cards to your brother, you had 13 left. How many cards did you give to your brother?

Answer 1

12 cards + 24 cards = 36 cards
36 cards - 13 cards = 23 cards
You gave your brother 23 cards

Answer 2

The answer is 23!

12 + 24 = 36 <- That's all of his baseball cards.
Now we will do 36 - 13 = 23 to see the number cards you've given to your brother.

Hope this helps :)