After a number is enlarged by 10 times, it is 30.78 more than the original number. What is the original number?
一个数扩大10倍后比原来的数增加了30.78，原数是多少．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">30.78 / 9</gadget>
<output>3.42</output>

<result>3.42</result>