In a newspaper, each one of 12 pages holds 2 photos and each of another 9 pages hold 3 photos. How many photos are used in the newspaper? Give the rationale and then the answer.
Let's think step by step. The number of photos in the first batch of pages is 12 * 2 = 24 photos. The number of photos in the second batch is 9 * 3 = 27 photos. The total number of photos used in the newspaper is 24 + 27 = 51 photos.. The answer is: 51.

Micah, Dean, and Jake are all training for a marathon organized by a local NGO to support children in their town who have cancer. Micah runs 2/3 times as fast as Dean. It takes Jake 1/3 times more time to finish the marathon than it takes Mica. If Dean takes 9 hours, what's the total time the three take to complete the marathon? Give the rationale and then the answer.
Let's think step by step. If Dean takes 9 hours to finish the marathon, it takes Micah 2 / 3 * 9 hours = 6 hours to finish the marathon. It takes Jake 1 / 3 * 6 hours = 2 more hours to finish the marathon than Micah. Jake takes a total of 6 hours + 2 hours = 8 hours to finish the marathon. Micah, Dean, and Jake take a total of 8 hours + 6 hours + 9 hours = 23 hours to finish the marathon.. The answer is: 23.

Carol is an aviation engineer deciding how much fuel to put in a jet. The empty plane needs 20 gallons of fuel per mile. Each person on the plane increases this amount by 3 gallons per mile, and each bag increases it by 2 gallons per mile. If there are 30 passengers and 5 flight crew, and each person brought two bags, how many gallons of fuel does the plane need for a 400-mile trip? Give the rationale and then the answer.
Let's think step by step. First find the total number of people by adding the number of passengers and flight crew: 30 people + 5 people = 35 people. Then find the total number of bags by doubling the total number of people: 35 people * 2 bags / person = 70 bags. Then find the fuel increase caused by the people by multiplying their number by the fuel increase per person: 35 people * 3 gallons / mile / person = 105 gallons / mile. Then multiply the number of bags by the fuel increase per bag to find the total fuel increase they cause: 70 bags * 2 gallons / mile / bag = 140 gallons / mile. Now add the fuel increases to the base fuel consumption to find the total fuel needed per mile: 140 gallons / mile + 105 gallons / mile + 20 gallons / mile = 265 gallons / mile. Now multiply the fuel consumption per mile by the number of miles flown to find the total amount of fuel needed: 265 gallons / mile * 400 miles = 106,000 gallons of fuel.. The answer is: 106000.