In a subtraction formula, the sum of the minuend, the subtrahend and the difference is 1, the difference is (1/4), what is the subtrahend.
在一个减法算式里，被减数、减数与差相加的和是1，差是(1/4)，减数是多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">(1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

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