If 3X=4y, then ((y)/(X))=((())/(())), when X=(2/5), y=how much.
如果3X=4y，那么((y)/(X))=((())/(()))，当X=(2/5)时，y=多少．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(3/4) * (2/5)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>