Answer:
14a
Explanation:
The greatest common factor is defined as the largest number by which the two given terms can be divided
The first given term is 14a, let's leave it as it is for now
The second given term is 28ab, this term can be rewritten as:
2 14a b
We can note that the 14 a is the largest factor by which the two terms can be divided
This means that the GCF of the two given terms is 14a
Hope this helps :)
