Subtract a whole tens number from 400, divide the difference by the whole number, the quotient is 9, what is the whole number.
从400里减去一个整十数，得到的差再除以这个整十数，商是9，这个整十数是多少．
<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<gadget id="calculator">400 / 10</gadget>
<output>40</output>

<result>40</result>