Audrey was asleep for 10 hours last night and dreamed for 2/5 of the time. How much of the night was she not dreaming?
If Audrey was asleep for 10 hours last night and dreamed for 2/5 of the time, she dreamed for 2/5*10 = 
<gadget id="calculator">10*2/5</gadget>
<output>4</output>
4 hours.
The total time Audrey slept without dreaming is 10-4 = 
<gadget id="calculator">10-4</gadget>
<output>6</output>
6 hours.

<result>6</result>