Factor each expression

1-9a^2/a+1 times 4x^2-y^2/x+y

Here is what I got:
(1-3a)(1+3a)/a+1 times (2x-y)(2x+y)/x+y

what am i doing wrong? The final answer is suppose to be 1-3a

You must have a typo in your question.

The first part contains the variable a, the second contains the variable x.

No way can that be the answer !