[Question]Beth is a scuba diver. She is excavating a sunken ship off the coast of a small Caribbean island and she must remain underwater for long periods. Her primary tank, which she wears when she first enters the water, has enough oxygen to allow her to stay underwater for 2 hours. She also has several 1-hour supplemental tanks that she takes with her as well as stores on the ocean floor so she can change tanks underwater without having to come up to the surface. She will need to be underwater for 8 hours. How many supplemental tanks will she need?
[Answer]For an 8 - hour dive, she will use her 2 - hour primary tanks and will need supplemental tanks for 8 - 2 = 6 additional hours. Since each supplemental tank holds 1 hour of oxygen, for 6 hours she will need 6 / 1 = 6 supplemental tanks. The answer is 6.

[Question]Lighters cost $1.75 each at the gas station, or $5.00 per pack of twelve on Amazon. How much would Amanda save by buying 24 lighters online instead of at the gas station?
[Answer]First find how many packs Amanda would have to buy on Amazon: 24 lighters / 12 lighters / pack = 2 packs. Then multiply that number by the cost per pack to find the total cost from Amazon: 2 packs * $5 / pack = $10. Then multiply the total number of lighters Amanda buys by the cost per lighter at the gas station: 24 lighters * $1.75 / lighter = $42. Then subtract the total Amazon cost from the total gas station cost to find the savings: $42 - $10 = $32. The answer is 32.

[Question]Dikembe wants to teach everyone at school about the importance of flossing, so he plans to bring enough packets of floss for everyone. There are 20 students in his class. Each student needs 1.5 yards of floss. He sees in the store that each packet of floss contains 35 yards. If he buys the least amount necessary, how much floss is left over?
[Answer]He will need to bring 30 yards of floss because 20 x 1.5 = 30. One packet of floss is enough because 35 > 30. He has 5 yards left over because 35 - 30 = 5. The answer is 5.

[Question]Mary and Ann are going sledding. Mary slides down a hill that's 630 feet long at a speed of 90 feet/minute. Ann slides down a hill that's 800 feet long at a rate of 40 feet/minute. How much longer does Ann's trip take than Mary?
[Answer]
First find the total time Mary's trip takes: 630 feet / 90 feet / minute = 7 minutes. Then find the total time Ann's trip takes: 800 feet / 40 feet / minute = 20 minutes. Then subtract Mary's time from Ann's time to find the difference: 20 minutes - 7 minutes = 13 minutes. The answer is 13.