Subtract the subtrahend from the minuend, the difference is 0.8, the sum of the minuend, the subtrahend and the difference is 3, what is the subtrahend.
被减数减去减数，差是0.8，被减数、减数与差的和是3，减数是多少．
<gadget id="calculator">3 - 0.8 - 0.8</gadget>
<output>1.4</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">1.4 / 2</gadget>
<output>0.7</output>

<result>0.7</result>