Charles bought 20 papers to draw. Today Charles drew 6 pictures. Yesterday he drew 6 pictures before going to work and some pictures when he came back. How many pictures did Charles draw when he came back from work knowing that he has 2 papers left?
Charles drew 6 + 6 = 
<gadget id="calculator">6+6</gadget>
<output>12</output>
12 pictures.
He has 20 - 12 = 
<gadget id="calculator">20-12</gadget>
<output>8</output>
8 papers left.
So Charles drew when he came back from work 8 - 2 = 
<gadget id="calculator">8-2</gadget>
<output>6</output>
6 pictures.

<result>6</result>