He takes pictures for 3 * 365 = 1095 days. So he takes 10 * 1095 = 10,950 pictures. That means he needs 10950 / 50 = 219 memory cards. So he spends 219 * 60 = $13140 on memory cards.
This justifies what answer for what question? Q & A:
John has taken 10 pictures every day for the past 3 years. He saves them in raw format so each memory card can store 50 images. Each memory card costs $60. How much does he spend on memory cards?
13140