X's (4/5) is 21 more than 39, find X.
X的(4/5)比39多21，求X．
<gadget id="calculator">39 + 21</gadget>
<output>60</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">60 / (4/5)</gadget>
<output>75</output>

<result>75</result>