[Question]: Percy wants to save up for a new PlayStation, which costs $500. He gets $200 on his birthday and $150 at Christmas. To make the rest of the money, he's going to sell his old PlayStation games for $7.5 each. How many games does he need to sell to reach his goal?
[Answer]: He needs to earn $150 more dollars because 500 - 200 - 150 = 150. He needs to sell 20 games because 150 / 7.5 = 20.
So the answer is 20.

[Question]: Mike spent 37 dollars on notebooks. He bought a total of 12 notebooks. He bought 3 red notebooks at 4 dollars each, 2 green notebooks at 2 dollars each, and the rest were blue notebooks. How much does each blue notebook cost?
[Answer]: He bought 12 - 3 - 2 = 7 blue notebooks. He paid 3 * $4 = $12 for red notebooks. He paid 2 * $2 = $4 for green notebooks. He spent $37 - $12 - $4 = $21 on blue notebooks. Each blue notebook costs $21 / 7 = $3.
So the answer is 3.

[Question]: Robi Ney wants to fill a 120-liter tub. He is amused by letting the water run for 1 minute, then closing the water supply for 1 minute, and so on alternating opening and closing the water supply. But the cap at the bottom of the tub is not very airtight and lets 1 liter of water escape per minute. The flow rate of the tap is 12 liters per minute. How long does it take to fill the tub in minutes?
[Answer]:
In 2 minutes, 12 liters of water flow into the bathtub and 2 liters (2 minutes x 1 liter / minute ) escape. This will leave 12 – 2 = 10 liters of water every two minutes. We can divide the number of liters by the number of minutes to find the average flow per minute, which is 10 / 2 = 5 liters per minute. To fill the tub, it will take 120 liters / 5 liters / min = 24 min.
So the answer is 24.