John starts at an elevation of 400 feet.  He travels downward at a rate of 10 feet down per minute for 5 minutes.  What is his elevation now?
He traveled down 10*5=
<gadget id="calculator">10*5</gadget>
<output>50</output>
50 feet.
So he is at an elevation of 400-50=
<gadget id="calculator">400-50</gadget>
<output>350</output>
350 feet.

<result>350</result>