50% of a certain number is exactly 40% of 3, what is this number?
某数的50%正好是3的40%，这个数是多少？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(2/5) / (1/2)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">3 * (4/5)</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>