Question 181648
There is two different ways to look at this  problem here....

(1) (3x/9x)-15  or 
(2) (3x)/(9x-15)

notice that in the first one the only numbers underneath the division sign are 9x while in the second one it is assumed that you have (9x-15) under the division sign...

your solution is correct if the problem is like (1) but if problem is like (2) you cannot separate the denominator...

(2)  http://www.algebra.com/algebra/homework/Polynomials-and-rational-expressions/Polynomials-and-rational-expressions.faq.question.181645.html