How can I apply multiple transformation to the same key in a Python dictionary : <p>I am an inventory manager, and my stock is as below</p>

<pre><code>oldstock = {"A":100,"B":120,"C":150,"D":100,"E":230,"F":200,"G":180,"H":140,"I":90,"J":50}
</code></pre>

<p>I sold some items from each bin as below however (seems as though a list of dictionaries was the best way to represent it)</p>

<pre><code>sale = [{"A":20},{"C":25},{"E":15},{"F":18},{"H":20},{"C":35},{"A":40},{"A":5},{"E":40},{"H":20}]
</code></pre>

<p>How can I calculate my new stock after making these sales per bin?</p>
