Suppose you have a wallet with $5 bills, $10 bills, and $20 bills. if the probability of picking a $20 bill is 4/15, and the probability of picking a $20 bill is 4/15, and the probability of picking a $5 bill is 1/3, what is the probability of picking a $20 bill?

The question does not make any sense. The probability of a 20 bill has already been given.

Given:
$5 bills
$10 bills
$20 bills

probability of $20 is 4/15
probability of $5 is 1/3

numerator is the number of events
denominator is the number of outcomes

the missing probability is of the $10 bill.

4/15 + 1/3 + x = 1 or 15/15

$5 bill = 1/3 x 5/5 = 5/15

15/15 - 4/15 - 5/15 = (15-4-5)/15 = (15-9)/15 = 6/15 = 2/5

the probability of $10 is 2/5