Probability of drawing dollar bills

A wallet containing 5 five-dollar bills, 7 ten-dollar bills, and 8 twenty-dollar bills is found and returned to its owner.  The wallet's owner will reward the finder with 1 bill drawn randomly from the wallet.  What is the probability that the bill drawn will be a twenty-dollar bill?
A.)  1/20
B.)  4/51
C.)  1/8
D.)  2/5
​E.)  2/3

---

number of successes 
-----------------------  =  probability
number of possibilities

8 bills are twenty-dollar bills (successes)
20 bills total  (possibilities)

 8
----  =  probability
20

D.)  2/5  {reduced}

​​Ask Algebra House