I need help on how to solve these problems (please do not give me the answers i just want to learn how to solve these types of problems :))

Part A: Find a rational number that is between 7.7 and 7.9. Explain why it is rational.

Part B: Find an irrational number that is between 7.7 and 7.9. Explain why it is irrational. Include the decimal approximation of the irrational number to the nearest hundredth.