Keywords:
Expression, variable, factor, GCF, factor
For this case we have an expression with a variable, in which we must factor the expression using the greatest common factor. By definition we have that the GFC of two numbers is the largest number that is a factor of both numbers.
Having said that we have the following expression:

So the greatest common factor between 15 and 65 is 5. So:

Answer:
The greatest common factor of the expression
is 5, then:
