In a subtraction formula, if the minuend is 17.2 more than the subtrahend and 12.8 more than the difference, what is the minuend?
在一道减法算式中，如果被减数比减数多17.2，比差多12.8，那么被减数是多少．
<gadget id="calculator">17.2 + 12.8</gadget>
<output>30</output>

<result>30</result>