Can you work out the answer to the last sum?

16, 36, 72?

To find for the last sum of 16, 36, and 72, we need to decompose all prime factors such as shown below:

16=16,8,4,2,1

36=36,18,9,3,1

72=72, 36,18,9,3,1

x=64,32,16,8,4,2,1

The value of x is 128. Therefore, the answer to the last sum is 16, 36, 72, 128.