100 students took the exam and 13 failed, find the pass rate.
100位同学应考，未通过13个，求通过率．
<gadget id="calculator">100 - 13</gadget>
<output>87</output>

<gadget id="calculator">87 / 100</gadget>
<output>87/100 = around 0.87</output>

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

<gadget id="calculator">(87/100) * 1</gadget>
<output>87/100 = around 0.87</output>

<result>87/100 = around 0.87</result>