A smartphone seller is offering a discount of 5% off for customers who buy at least 2 smartphones at once. Melinda, Zoe and Joel want to buy an iPhone X each. If an iPhone X costs $600, how much can they save by pooling their money together and buying three iPhones at once from this seller rather than buying individually?
Let's think: Each iPhone X cost $600 so three iPhone Xs without the discount would cost 3 * $600 = $1800. The discount is 5% and 5% of $1800 is (5 / 100) * $1800 = $90 which is what they get to save by buying collectively.. The answer is: 90.

A roadwork company is paving a newly constructed 16-mile road. They use a mixture of pitch and gravel to make the asphalt to pave the road. Each truckloads of asphalt uses two bags of gravel and five times as many bags of gravel as it does barrels of pitch to make. It takes three truckloads of asphalt to pave each mile of road. The company paved 4 miles of road on one day, then one mile less than double that on the second day. How many barrels of pitch will the company need to finish the remaining road on the third day?
Let's think: On the second day, the company paved 4 * 2 - 1 = 7 miles. The company has 16 - 7 - 4 = 5 miles of road remaining to pave. They will need 3 * 5 = 15 truckloads of asphalt to pave 5 miles of road. For 15 truckloads, they will need 15 * 2 = 30 bags of gravel. Thus, the company will need 30 / 5 = 6 barrels of pitch to finish the road on the third day.. The answer is: 6.

50% of substitute teachers walk out after 1 hour of teaching. 30% of the remainder quit before lunch. If 60 substitute teachers show up at 7 AM, how many will be left after lunch?
Let's think: First find the number of substitute teachers left after half quit: 60 teachers / 2 = 30 teachers. Then find how many teachers quit after an hour but before lunch: 30 teachers * 30% = 9 teachers. Then subtract that number from the number of teachers left after one hour to find how many are left after lunch: 30 teachers - 9 teachers = 21 teachers.. The answer is: 21.

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?
Let's think:
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.