Answer:
This situation represents a function. The domain is {A, B, C, D, E} and the range is {$5, $10, $20, $50, $100}.
Explanation:
Firstly, we need to know what a function is:
It is simply something that relates an input to an output. Like for instance a mirror is a function that relates your face to your image. In lay terms we can call something a function if and only if it can relate one thing to another. Mathematically, a function is called a function if and only if every input has a distinct output, just as how one face can't produce two images at a time when looked at the mirror. The input is called the domain and output range.
Now, in the question we are told that all the bills are mapped – related in lay terms – to some set of coins that are exactly the same number of the bills. This means each bill has a distinct input. Here is a clearer picture:
A to 5 usd
B to 10usd
C to 20usd
D to 50usd
E to 100usd
Where A, B, C, D and E respectively stand for the distinct coins that are mapped to the distinct bill.
From here, each coin has it distinct output. Therefore it is a function.
The domain is {A, B, C, D, E} and the range is {$5, $10, $20, $50, $100}.