About the order of a difference equation The question is related to a statement in a dsp book.  I am attaching the image of the statement.  In the attached image, is the equation 1.5 a difference equation of order 1 as stated in the book?  I think it is of order 0 since there is no feedback term i.e. no y(n-1).
To my understanding, the order of a difference equation is equal to the maximum delay, regardless if its delay on the input or output side. So, you have two first-order difference equations here.