Alright! So, we know that the GCF is 6 because it's the the highest number that can go into 48 & 18.
That means, to find what in the blanks, you just need to reverse the math.
48/6 = 8
18/6 = 3
So the number in the first blank is 8 and the number in the second blank is 3.
Let me know if you're still confused.