7.5 means the amount of milligrams in the narcotic compound hydrocodone which is a synthetic to coedine, 500 is the milligram in the amount of tylenol taken, it come in 2.5, 5., 7.5 and 10 milligrams, becareful if you have never taken this medication before, its pretty strong. It can become very addictive, it gives a "euphoric" feeling that everything is alright with the world around, when in fact it may or may not be, if driving with this narcotic, be extra careful, its full of illusions and delusional behavior, may or may not affect you in this way, but, if ever pulled over by law enforcement, they can administer a "breath test" on you and determine what you are under the influence of, which will lead to a "DUI", driving under the influence, it happened to my mom. On the other hand, it may not affect you at all in this way if you have a high tolerance of certain medications, either way, be careful with it, too much of it can lead to overdose.
Source(s):
past experience with my mother