In a 90-minute soccer game, Mark played 20 minutes, then rested after. He then played for another 35 minutes. How long was he on the sideline?
Mark played for a total of 20 + 35 = 
<gadget id="calculator">20+35</gadget>
<output>55</output>
55 minutes.
So, he was on the sideline for 90 - 55 = 
<gadget id="calculator">90-55</gadget>
<output>35</output>
35 minutes.

<result>35</result>