Answer:
4x
Explanation:
the answer is 4x because 8/4 is 2 which means It can go and also we can see x in 8x^3 so x can also go in it and in the second equation 12/4 is 3 so 4 can also go and only one x is there too so that means x is both common in both numbers which makes 4x common in both numbers.