(1/3) of a number is 4 more than 20% of this number, what is this number?
一个数的(1/3)比这个数的20%多4，这个数是多少？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/3) - (1/5)</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">4 / (2/15)</gadget>
<output>30</output>

<result>30</result>