When Xiao Ming calculated a decimal subtraction problem, he regarded the subtrahend 6.9 as 9.6, and the calculated difference was 15.48. What should be the correct difference?
小明在计算一道小数减法题时，把减数6.9看成了9.6，结果算出的差是15.48，正确的差应该是多少？
<gadget id="calculator">9.6 - 6.9</gadget>
<output>2.7</output>

<gadget id="calculator">15.48 + 2.7</gadget>
<output>18.18</output>

<result>18.18</result>