Chris buys 2 and a half dozen donuts on his way to work to share with his co-workers.  While driving, he eats 10% of the donuts.  Once inside, he grabs another 4 donuts for his afternoon snack.  How many donuts are left for his co-workers?
He buys 2 and a half dozen donuts so that's 2.5*12 = 
<gadget id="calculator">2.5*12</gadget>
<output>30</output>
30 donuts.
He eats 10% of the donuts on his way to work so he eats .10*30 = 
<gadget id="calculator">10*.01*30</gadget>
<output>3</output>
3 donuts.
He bought 30 donuts and ate 3 so that leaves 30-3 = 
<gadget id="calculator">30-3</gadget>
<output>27</output>
27 donuts.
Once inside, he grabs another 4 donuts of his afternoon snack so that leaves 27-4 = 
<gadget id="calculator">27-4</gadget>
<output>23</output>
23 donuts for his co-workers.

<result>23</result>