Explain how to calculate these mentally.

1. 15 is what percentage of 30?
2. 3 is what percentage of 12?
3. 6 is what percentage of 10?

Noah says that to find 20% of a number he divides the number by 5. For example, 20% of 60 is 12, because \(60 \div 5 = 12\). Does Noah’s method always work? Explain why or why not.

Diego has 75% of \$10. Noah has 25% of \$30. Who has more money? Explain your reasoning.

Two ants are at the opposite end of a 22-meter long cable. They start walking toward each other at the same time, each at a constant speed. The smaller ant walks at a speed of 2.5 meters per minute. The larger ant walks at a speed of 3 meters per minute.

Here is a table showing the distances the ants traveled and how far apart they are over time. Use the table to find how much time passes before they meet.