The (9/20) of a number is 3 less than its (1/2), what is this number?
一个数的(9/20)比它的(1/2)少3，这个数是多少？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">9 / 20</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(1/2) - (9/20)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">3 / (1/20)</gadget>
<output>60</output>

<result>60</result>