If you sell a pair of shoes for 100 yuan, you can earn 25%. If you sell them for 90 yuan, how much can you earn?
一双鞋子，如果卖100元，可赚25%，如果要卖90元可赚多少
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">100 / (5/4)</gadget>
<output>80</output>

<gadget id="calculator">90 - 80</gadget>
<output>10</output>

<gadget id="calculator">10 / 80</gadget>
<output>1/8 = around 0.125</output>

<result>1/8 = around 0.125</result>