Subtract the subtrahend from the minuend, the difference is 0.4, the sum of the minuend, the subtrahend and the difference is 2, what is the subtrahend.
被减数减去减数，差是0.4，被减数、减数与差的和是2，减数是多少．
<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 - 0.4</gadget>
<output>0.6</output>

<result>0.6</result>