To find the probability of picking a five dollar bill and then another five dollar bill, you will find the chance of picking a five dollar bill the first time, and multiply by the probability of picking another one the second time.
There is a 3 out of 9 chance the first time because there are 3 - $5 dollar bills, and 9 total bills.
The second time there will be a 2 out of 8 chance, because if you picked a $5 dollar bill the first time, there should be 2 - $5 bills left and 8 total bills.
First what you would have to do is distribute the reciprocal to the (d/3 + 2) and the d/3 is canceled out. You are left with h=6/d. When you put the h over 1 in a fraction, it stays the same. Like in trig, you switch the d and the h and you have d/1=6/h.
