Joseph gave 23 cards to each of his 15 students and had 12 cards left. How many cards did Joseph have at first? Give me reasons, before answering the question
He gave 23 cards each to 15 students for a total of 23 * 15 = 345 cards. He has 12 cards left, so originally the number of cards was 345 + 12 = 357 cards. So the final answer is 357.