If we could tell the 5's apart, there would be:

4 ways to place the 3.
3 ways to place the first 5.
2 ways to place the second 5.
1 way to place the 1.

The answer would be (4)(3)(2)(1) = 24 ways.
However since we cannot tell the first 5 from the second 5,
we must divide by the number of ways they can be switched,
which is 2 ways.

Answer: 24/2 = 12 ways.  Here they are listed:

 1. 3558
 2. 3585
 3. 3855
 4. 5358
 5. 5385
 6. 5538
 7. 5583
 8. 5835
 9. 5853
10. 8355
11. 8535
12. 8553

Edwin