Gnuff charges a flat rate of $20 per tutoring session plus $7 per minute. The total amount paid for Gnuff for tutoring for one session is $146. How many minutes did Gnuff tutor for?
First find the amount paid just for the per-minute fee, which is $146 - $20 = $
<gadget id="calculator">146-20</gadget>
<output>126</output>
126.
Then divide that number by the per-minute rate to find the number of minutes: $126 / $7 per minute = 
<gadget id="calculator">126/7</gadget>
<output>18</output>
18 minutes.

<result>18</result>