Answer: Common ratio is

Step-by-step explanation: Given sequence −15,−9,−275,−8125,...
The general terms of a geometric sequence are:
.
In common ratio is given by dividing next term from previous term

Therefore, in order to find the common ratio for the given geometric sequence, we need to divide second term by first term or third term by second term.
Dividing second term by first term, we get

Dividing top and bottom by -3, we get
.
Therefore, common ratio is
