I had to take a urine test and tested positive for cocaine. I was
taking two perscription medications propoxyphene and hydrocodone. what
is the percentage of medication in one system would cause this to
happen. how can i fix this problem?

Just like to clarify, did you the test show cocaine positiveness or
just positiveness for any prohibited drug? I asked because the first
drug you mentioned, propoxyphene, is on the list of prohibited or
controlled drugs, the list cocaine is on. This was probably the one
detected and test read out positive that you were using a controlled
substance. You might be able to show your prescription for this drug,
if you have one, or any medical records to justify your taking. If you
have no authorization for its use, you might get into trouble.

dip your finger in bleach, let it dry, then stir the sample with that finger.