What is the number after increasing 40% of a certain number to 84?
某数增加它的40%后是84，这个数是多少．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + (2/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">84 / (7/5)</gadget>
<output>60</output>

<result>60</result>