If one "AVN" is half the price of one "The Dark" CD, that means one CD of "The Dark" costs 12 * 2 = $24. So for two "The Dark" CDs, Alan needs to pay 24 * 2 = $48. So all CDs cost by now 12 + 48 = $60. The 90s music CDs cost 40 / 100 * 60 = $24. That means for all CDs Alan needs to pay 60 + 24 = $84.
The answer: 84
Reverse engineering the question: Alan likes to support music creators, so instead of downloading songs from the internet, he visits a record store once in a while. He decided now to buy 2 CDs by "The Dark", 1 CD by the creator "AVN", and 5 CDs that are mixes of songs from the 90s. The price of the "AVN" CD is $12 and it is half the price of one CD by "The Dark". The 5 CDs of 90s music cost is 40% of all the cost of all other CDs Alan is going to buy. How much will Alan have to pay for all the products?

First find how much water fills the bathtub per hour: 40 ml / minute * 60 minutes / hour = 2400 ml / hour. Then subtract the water that evaporates to find the total amount of water added per hour: 2400 ml / hour - 200 ml / hour = 2200 ml / hour. Then multiply that amount by the number of hours to find the total amount of water in the tub: 2200 ml / hour * 9 hours = 19800 ml. Then find the number of milliliters in 12 liters: 12 liters * 1000 ml / liter = 12000 ml. Then subtract the water Jack removes from the total amount of water to find the remaining amount of water: 19800 ml - 12000 ml = 7800 ml.
The answer: 7800
Reverse engineering the question: Jack leaves his bathtub's faucet dripping at a rate of 40 ml/minute. Water evaporates from the bathtub at a rate of 200 ml/hour. If he leaves the water running for 9 hours, then dumps out 12 liters, how many milliliters of water are left in the bathtub?

He now has 150 + 50 = 200 subscribers. So he makes 200 * 9 = $1800 a month.
The answer: 1800
Reverse engineering the question: James streams on twitch. He had 150 subscribers and then someone gifted 50 subscribers. If he gets $9 a month per subscriber how much money does he make a month?

If Coco used his oven 25 hours last month and its energy consumption is 2.4 kW per hour, then we consumed a total of 25 * 2.4 = 60 kW on his oven last month. If the price of electricity is $0.10 per kW, then 60 kW would cost = $0.10 * 60 = $6.
The answer: 6
Reverse engineering the question:
The electricity price in Coco's town is $0.10 per kW. Coco's new oven has a consumption rate of 2.4 kWh (kilowatt-hours). How much will Coco pay for using his oven only if he used it for a total of 25 hours last month?