Answer: 8
Explanation:
One way to find the GCF (Greatest Common Factor) is to list the factors of each number and find the largest factor that they have in common.The factors of 16 are: 1, 2, 4, 8, 16
The factors of 8 are: 1, 2, 4, 8
The largest factor that 16 and 8 have in common is 8.
This means that the marbles can be divided into 8 identical groups, each containing 2 blue marbles and 1 white marble.
Therefore, the greatest number of groups Spencer can make is 8.