After the decimal point of a number is moved one place to the right, the number obtained is 31.5 more than the original number. What is the original number?
一个数的小数点向右移动一位后，得到的数比原数增加了31.5，原来的数是多少．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">31.5 / 9</gadget>
<output>3.5</output>

<result>3.5</result>