In a subtraction formula, the sum of the subtrahend, the subtrahend and the difference is 13.5, and the subtrahend is 0.25 smaller than the difference. What is the difference?
在一个减法算式里被减数、减数和差的和是13.5，减数比差小0.25，求差是多少？
<gadget id="calculator">13.5 / 2</gadget>
<output>6.75</output>

<gadget id="calculator">6.75 + 0.25</gadget>
<output>7</output>

<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<result>7/2 = around 3.5</result>