[Question]: John cuts his grass to 2 inches. It grows .5 inches per month. When it gets to 4 inches he cuts it back down to 2 inches. It cost $100 to get his grass cut. How much does he pay per year?
[Answer]: He cuts his grass 4 - 2 = 2 inches. So he gets it cut every 2 / .5 = 4 months. That means he gets it cut 12 / 4 = 3 times a year. So he pays 100 * 3 = $300 per year.
So the answer is 300.

[Question]: John decides to get a new apartment with a roommate. His former rent was $2 per square foot for a 750 square foot apartment. His new apartment cost $2800 per month, which he splits evenly with the roommate. How much money does he save a year?
[Answer]: His old apartment cost 750 * $2 = $1500 a month. His new apartment cost $2800 / 2 = $1400 a month. So he saves $1500 - $1400 = $100 a month. That means he saves $100 * 12 = $1200 a year.
So the answer is 1200.

[Question]: Whitney’s mom gave her two $20 bills to spend at the school book fair. Whitney has decided to buy 2 posters, 3 notebooks, and 2 bookmarks. Each poster costs $5, each notebook costs $4, and each bookmark costs $2. How much money, in dollars, will Whitney have left over after the purchase?
[Answer]:
Whitney is buying 2 posters for $5 each, so the posters will cost 2 * $5 = $10 total cost for posters. Whitney is buying 3 notebooks for $4 each, so the notebooks will cost 3 * $4 = $12 total cost for notebooks. Whitney is buying 2 notebooks for $2, so the bookmarks 2 * $2 = $4 total cost for bookmarks. Since Whitney is paying $10 for posters, $12 for notebooks, and $4 for bookmarks, her total purchase will cost $10 + $12 + $4 = $26 total purchase cost. Whitney’s mom gave her 2 $20 bills, so she will be paying with 2 * $20 = $40 total payment. Since Whitney is paying with $40 and her purchase cost will be $26, she will have $40 - $26 = $14 left over after the purchase.
So the answer is 14.