Bryan's score on a math exam is 20. Jen scored 10 more than Bryan while Sammy scored 2 fewer than Jen. If the math exam has 35 points in all, how many mistakes did Sammy make?
Jen scored 20 + 10 = 
<gadget id="calculator">20+10</gadget>
<output>30</output>
30 on the exam.
Sammy scored two less, so his score was30 - 2 = 
<gadget id="calculator">30-2</gadget>
<output>28</output>
28.
Thus, Sammy made 35 - 28 = 
<gadget id="calculator">35-28</gadget>
<output>7</output>
7 mistakes.

<result>7</result>