title: Return change with certain number of coins
body: <p>I want to implement an automatic coffee vending machine.  The machine is pre-filled with coins (for instance 10 5-cent coins, 20 10-cent coins, etc). </p>
  
  <p>I want the user to enter a certain amount (insert money) subtract the price of the coffee (e.g 120 cents) and then give change back based on the coins available in the vending machine.</p>
  
  <p>I started like this:</p>
  
  <pre><code>final int [] coins = {200, 100, 50, 20, 10, 5}; 
  </code></pre>
  
  <p>...but how can I give them a value like 10 = 5 cause there are 5 10-cent coins?</p>