Rex is taking lessons for his driver’s license. He wants to take 40 hour-long lessons before his test, and decides to have two-hour sessions twice a week until he has done his test. After 6 weeks, how many more weeks will Rex need to continue taking lessons to reach his goal?
Each week, Rex is taking 2 hour-long lessons * 2 times a week = 
<gadget id="calculator">2*2</gadget>
<output>4</output>
4 lessons.
After 6 weeks, he has done 4 lessons per week * 6 weeks = 
<gadget id="calculator">4*6</gadget>
<output>24</output>
24 lessons.
So Rex still needs 40 total lessons - 24 lessons taken = 
<gadget id="calculator">40-24</gadget>
<output>16</output>
16 lessons.
He will therefore need lessons for another 16 lessons / 4 lessons per week = 
<gadget id="calculator">16/4</gadget>
<output>4</output>
4 weeks.

<result>4</result>