(2/5) of the number A is (3/10) of the number B, how much less the number A is than the number B.
甲数的(2/5)是乙数的(3/10)，甲数比乙数少多少．
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

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

<gadget id="calculator">(3/10) / (2/5)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) / 1</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>