John decides to replace all his VHS with DVDs.  He can trade in his VHS for $2 each and then buy the DVDs for $10 each.  If he has 100 movies, how much does it cost to replace his movies?
It cost 10-2=$
<gadget id="calculator">10-2</gadget>
<output>8</output>
8 to replace each movie.
So it would cost 8*100=$
<gadget id="calculator">8*100</gadget>
<output>800</output>
800 to replace everything.

<result>800</result>