The difference of a subtraction formula is 16. If the minuend remains the same and the subtrahend increases by 4, what is the difference?
一道减法算式的差是16，如果被减数不变，减数增加4，则差是多少．
<gadget id="calculator">16 - 4</gadget>
<output>12</output>

<result>12</result>