In a subtraction formula, the sum of the minuend, the subtrahend and the difference is 100, and the subtrahend and the difference are equal. What is the difference?
在一个减法算式里，被减数、减数与差这三个数的和是100，其中减数与差相等，差是多少．
<gadget id="calculator">100 / 2 / 2</gadget>
<output>25</output>

<result>25</result>