It is known that the sum of minuend, subtrahend and difference is 58.4, if the subtrahend is 17.9, then what is the difference.
已知被减数、减数、差的和是58.4，如果减数是17.9，那么差是多少．
<gadget id="calculator">58.4 / 2</gadget>
<output>29.2</output>

<gadget id="calculator">29.2 - 17.9</gadget>
<output>11.3</output>

<result>11.3</result>