We are asked to find out the GCF of the given expression
GCF (greatest common factor) is the greatest common factor between two or more numbers.
To find the GCF, let us first list out the common factors of both numbers
Factors of 13 = 1, 13
Factors of 39 = 1, 3, 13, 39
Now which factor is common to both and is greatest?
Yes, it is 13
Therefore, the GCF of the given expression is 13
