When Xiaohong is calculating a subtraction problem, she regards the 9 in the subtrahend as 6, and the 4 in the subtrahend as 7. The result of her calculation is 15.4. What is the correct result?
小红在计算一道减法题时，把被减数个位上的9看成了6，把减数十分位上的4看成了7，她计算的结果是15.4，正确的结果是多少？
<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<gadget id="calculator">0.7 - 0.4</gadget>
<output>0.3</output>

<gadget id="calculator">3 + 0.3</gadget>
<output>3.3</output>

<gadget id="calculator">15.4 + 3.3</gadget>
<output>18.7</output>

<result>18.7</result>