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? Give the rationale and then the answer.
Let's think step by step. 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 is: 108.

Larry spent $5 for lunch and gave his brother $2. How much did Larry have at the beginning if he has $15 now? Give the rationale and then the answer.
Let's think step by step. Larry spent a total of $5 + $2 = $7. He has $15 + $7 = $22 at the beginning.. The answer is: 22.

Henry drinks 15 bottles of kombucha every month. Each bottle costs $3.00 and is eligible for a cash refund of $0.10 per bottle when he takes it to a recycling center. After 1 year, how many bottles of kombucha will he be able to buy after he receives his cash refund? Give the rationale and then the answer.
Let's think step by step. He drinks 15 bottles every month and there are 12 months in 1 year so that's 15 * 12 = 180 bottles. He earns $0.10 on every bottle that he recycles so that's .10 * 180 = $18.00. He has $18.00 and each bottle costs $3.00 so he can buy 18 / 3 = 6 bottles.. The answer is: 6.