20% of a number is 15 more than 5% of the number. What is this number?
一个数的20%比这个数的5%多15．这个数是多少？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/5) - (1/20)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">15 / (3/20)</gadget>
<output>100</output>

<result>100</result>