In a subtraction formula, the sum of the minuend, the subtrahend and the difference is 42, and the subtrahend is 16.2. What is the difference?
在一道减法算式中，被减数、减数和差的和是42，其中减数是16.2，差是多少？
<gadget id="calculator">42 / 2</gadget>
<output>21</output>

<gadget id="calculator">21 - 16.2</gadget>
<output>4.8</output>

<result>4.8</result>