Answer: 8
Step-by-step explanation: You can factor out 32, 48, and 72 by using prime factorization which is listing all of the PRIME factors for each number
32: 2 x 2 x 2 x 2 x 2
48: 3 x 2 x 2 x 2 x 2
72: 3 x 3 x 2 x 2 x 2
If you look at all the prime factors, 2 appears in every number 3 times, so you do 2x2x2 to get the final answer, which is 8.