Answer:
Factors of 15: 1, 3, 5 and 15.
Factors of 17: 1 and 17.
Factors of 26: 1, 2, 13 and 26
Factors of 80: 1, 2, 4, 8, 10, 20, 40, and 80.
Actually you can find all the answers in the Internet.
