We have a 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?
And an answer: 20
So how you got the answer?
He needs to earn $150 more dollars because 500 - 200 - 150 = 150. He needs to sell 20 games because 150 / 7.5 = 20.

We have a 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?
And an answer: 3
So how you got the 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.

We have a 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?
And an answer: 24
So how you got the 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.