(4/15) of a number is (2/5) of 50, what is this number?
一个数的(4/15)是50的(2/5)，这个数是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 / 15</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">(2/5) / (4/15)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">50 * (3/2)</gadget>
<output>75</output>

<result>75</result>