The minuend is 420, the ratio of the subtrahend to the difference is 2:5, what is the difference.
被减数是420，减数与差的比是2：5，差是多少．
<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">420 / 7</gadget>
<output>60</output>

<gadget id="calculator">60 * 5</gadget>
<output>300</output>

<result>300</result>