Determine whether each sequence is arithmetic , geometric , or neither. explain. 108, 66, 141, 99

Be sure to know and understand the following:

If there is a common difference between terms of a sequence, the sequence is arithmetic.  Example:  108 110 112 114 (common diff is 2).  But with 108, 66, 141, 99, the diff between 108 and 66 is -42; the diff between 66 and 141 is 77; and so on.  -42 and 77 are not the same.  So, what do you conclude?

If there is a common ratio, the sequence is geometric.  Example:  108, 216, 324, 648.  What do you conclude about the given sequence?