To apply for a library card, you must bring your valid ID card and deposit 50 yuan. You can return the card if you return it. 30 yuan can register every year, and Cary can deposit some money appropriately, whether it is 10 yuan or 20 yuan. It doesn't matter if you don't save it Each card can borrow three books at the same time, within 30 days, and each book will be returned after 30 days. 05 yuan/day, deducted from the card money. To apply for a card for the first time, you must go to 80 yuan at least, and it is enough to bring 100 yuan.