Answer this question:Paul is working at a university. He is part of a big project, which involves 70 scientists in total. Half of them are from Europe and one-fifth are from Canada. The rest are from the USA. How many scientists in this project are from the USA?
Of all the scientists taking part in the project, half of them are from Europe, which means 70 * 0.5 = 35 people. The number of researchers from Canada is 70 * 1 / 5 = 14 people. That means there are 70 - 35 - 14 = 21 researchers from the USA.
The answer is 21.

Answer this question:Hannah hangs a 2 foot by 4 foot painting on a 5 foot by 10 foot wall. What percentage of the wall is taken up by the painting?
First find the area of the painting: 2 feet * 4 feet = 8 square feet. Then find the area of the wall: 5 feet * 10 feet = 50 square feet. Then divide the area of the painting by the area of the wall and multiply by 100% to express the answer as a percentage: 8 square feet / 50 square feet * 100% = 16%.
The answer is 16.

Answer this question:Emily can type 60 words per minute. How many hours does it take her to write 10,800 words?
In an hour, Emily can type 60 words * 60 minutes = 3600 words. It will take her 10800 / 3600 = 3 hours to write 10800 words.
The answer is 3.

Answer this question:Ruby is taking dance lessons. They cost $75 for 10 classes in one pack. She can add additional classes at the price of 1/3 more than the average price of a class on the lesson in the pack. if she takes 13 total classes, how much does she pay?
The classes in the pack cost $7.5 each because 75 / 10 = 7.5. An additional class costs $10 because 7.5 x (1 + (1 / 3)) = 10. She buys 3 extra classes because 13 - 10 = 3. Her three additional classes cost $30 because 3 x 10 = 30. Her total cost is $105 because 75 + 30 = 105.
The answer is 105.