Question: Bob buys nose spray. He buys 10 of them for a "buy one get one free" promotion. They each cost $3. How much does he pay?
Answer: He got 10 / 2 = 5 paid. That means he paid 5 * 3 = $15. The answer is 15.

Question: Leah bought 3 boxes of birdseed. When she went to put them away, she discovered that she already had 5 boxes in the pantry. Her parrot eats 100 grams of seeds each week and her cockatiel eats 50 grams of seeds in a week. If each box of birdseed contains 225 grams, for how many weeks can she feed her birds without going back to the store?
Answer: In a week, her birds eat a total of 100 grams + 50 grams = 150 grams of seed each week. Leah has a total of 3 + 5 = 8 boxes of birdseed. The boxes of birdseed contain a total of 8 * 225 grams = 1800 grams. This is enough birdseed to feed her pets for 1800 / 150 = 12 weeks. The answer is 12.

Question: I run 12 miles in 90 minutes. What is my average speed in miles per hour?
Answer: First convert 90 minutes to hours: 90 minutes / 60 minutes / hours = 1.5 hours. In 1 hour, I run 12 miles / 1.5 hours = 8 miles / hour. The answer is 8.

Question: One set of barrettes costs $3 each, and one comb costs $1 each. Kristine buys one set of barrettes and one comb. Crystal buys three sets of barrettes and one comb. How much do the two girls spend altogether?
Answer:
Kristine spends $3 + $1 = $4. Three sets of barrettes cost 3 x $3 = $9. Crystal spends $9 + $1 = $10. Therefore, the two girls spend $4 + $10 = $14. The answer is 14.