(6/13) of a number is 30, what is (2/5) of this number.
一个数的(6/13)是30，这个数的(2/5)是多少．
<gadget id="calculator">6 / 13</gadget>
<output>6/13 = around 0.461538</output>

<gadget id="calculator">30 / (6/13)</gadget>
<output>65</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">65 * (2/5)</gadget>
<output>26</output>

<result>26</result>