The speed of Xiaohong going to school is 100m/min, and the average speed of going to school and leaving school is 80m/min, what is Xiaohong's speed after school?
小红上学的速度是100m/min，上学和放学的平均速度是80m/min，小红放学的速度是多少？
<gadget id="calculator">2 / 80</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">1 / 100</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">(1/40) - (1/100)</gadget>
<output>3/200 = around 0.015</output>

<gadget id="calculator">1 / (3/200)</gadget>
<output>200/3 = around 66.666667</output>

<result>200/3 = around 66.666667</result>