3
To clarify:
The prime factors of 45 are 3, 3, and 5 (or 32, 5.)
The prime factors of 60 are 2, 2, 3, and 5 (or 22, 3, 5.)
Therefore, the common factors are 1, 3, 5, and 15, while the common prime factors are only 3 and 5.
The highest common integral factor is 5, because 25 = 52, five is an integral factor of both 45 and 60, and 25 is not an integral factor of either 45 or 60.
the GCF of 45 and 60 is 15
The greatest common factor of the numbers 45 and 60 is 15.
For 45, 60, 90 the GCF = 15
1
15
15
15
15
15
The highest common factor 15
The Greatest Common Factor (GCF) is: 15