Brainliest to best, show all work but keep it simple and easy to understand use the sequence to answer the following question: 2.5, 6, 9.5, 13, 16.5, 20, … what is the common difference?

The common difference in an arithmetic sequence refers to the number that represents the difference between two terms in the sequence. 

When you look to the sequence you can see that from a term to other one the numbers are increasing, meaning that the common difference needs to be positive. To find the value of the common difference in an arithmetic sequence you have to select two terms. On this case 2.5 and 6, and 16.5 and 20.

Common Difference= 6-2.5
Common Difference= 3.5

Common Difference= 20-16.5
Common Difference= 3.5

After some calculations, you can conclude that the number representing the common difference in this arithmetic sequence is 3.5.

Looks pretty good to me!