Factor the each monomial.
25a = 5 · 5 · a
30b = 2 · 3 · 5 · b
The GCF is the product of the common prime factors in each monomial.
GCF = 5
The greatest common factor of 25a and 30b is 5.
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")