What are three pairs of numbers that have the greatest common factor of 5?

Answer 1

GCF or "greatest common factor" is the largest number made of factors common to each of a set of numbers. If all three have only a single 5 as common factor, it is the GCF.

15 and 20 (3x5 and 2x2x5) have a GCF of 5.

65 and 75 (13x5 and 3x5x5).

85 and 100 (17x5 and 2x2x5x5).

The trivial answer is "5" and any other multiple of 5.
5, 10

10, 15

5, 15

Answer 2

Select any three numbers, X, Y and Z that are mutually coprime: that is to say, their only common factor is 1. The 5X, 5Y and 5Z will meet your requirements.

So, if you consider the triple (4, 5, 6) then the numbers 20, 25 and 30 are your answer.