Carl buys index cards for his class. He gives each student 10 index cards. He teaches 6 periods a day and each class has 30 students. If a 50 pack of index cards cost $3 how much did he spend on them all? Let's be accurate as possible.
He has 30 * 6 = 180 students. So he needs to buy 180 * 10 = 1800 index cards. That means he needs to buy 1800 / 50 = 36 packs of index cards. So he spends 36 * 3 = $108.
The answer: 108.