If a number is reduced by 30%, it is 6.3. What is the number?
一个数减少30%后是6.3，这个数是多少．
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">6.3 / (7/10)</gadget>
<output>9</output>

<result>9</result>