Josephine has the same amount of 20 bills as she has 1 bills

Solution

Answer: 2 bills of $1, 6 bills of $5 and 2 bills of $20 (As explained below)

Let x, y and z be the number of $1, $5 and $20 bills, respectively. Then, as per given conditions we have:

z = x_________(1)

y = x + 4____________(2)

1x + 5y + 20z = 72___________(3)

Using substitution,we get:

1x + 5(x + 4) + 20x = 72

1x + 5x + 20 + 20x = 72

26x = 52

x = 2

Therefore, z = 2 and y = 6

Cross-check: $1(2) + $5(6) + $20(2) = $2 + $30 + $40 = $72.