The minuend is 40, the ratio of the subtrahend to the difference is 7:3, how much is the ratio of the subtrahend to the difference.
被减数是40，减数与差的比是7：3，减数比差多多少．
<gadget id="calculator">7 + 3</gadget>
<output>10</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(7/10) - (3/10)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">40 * (2/5)</gadget>
<output>16</output>

<result>16</result>