Q: In a classroom there are 30 students. 1/3 of them are boys. Among the girls, 40% own dogs, 20% own a cat, and the rest have no pets. How many girls in the class have no pet?
A: 2 / 3 students are girls because 1 - (1 / 3) = 2 / 3. 20 students are girls because 30 x (2 / 3) = 20. 40% of the girls don't have any pets because 100 - 40 - 20 = 40. 8 girls in class have no pets because 20 x .4 = 8. The answer is 8.

Q: Troy makes soup. He buys 4 pounds of beef and 6 pounds of vegetables. The vegetables cost $2 per pound and the beef is 3 times that price. How much does everything cost?
A: The vegetables cost 2 * 6 = $12. The beef cost 2 * 3 = $6 per pound. So the beef cost 4 * 6 = $24. So the total cost is 12 + 24 = $36. The answer is 36.

Q: 3 lions and 2 rhinos escape from the zoo. If it takes 2 hours to recover each animal how long did the zoo spend recovering animals?
A:
They had to recover 3 + 2 = 5 animals. So it took 5 * 2 = 10 hours to recover everyone. The answer is 10.