There are 20 hands in Peter’s class, not including his. Assume every student in the class has 2 arms and 2 hands. How many students are in Peter’s class including him?
There are 20 + 2 of Peter's hands = 
<gadget id="calculator">20+2</gadget>
<output>22</output>
22 hands in Peter's class including his.
There are 22 hands / 2 hands per student = 
<gadget id="calculator">22/2</gadget>
<output>11</output>
11 students.

<result>11</result>