Feifei’s school starts class at 7:50, Feifei starts from home to school at 7:35, walks 13 minutes on the road, how many minutes before Feifei arrives at school
飞飞所在学校7：50上课，飞飞7：35从家出发到学校，路上走了13分，飞飞到校提前多少分到校
<gadget id="calculator">35 + 13</gadget>
<output>48</output>

<gadget id="calculator">50 - 48</gadget>
<output>2</output>

<result>2</result>