When a classmate was doing a one-digit subtraction problem, he regarded the 1 in the ones place of the subtrahend as 7, and the 7 in the tenths place of the subtrahend as 1, and the result was that the difference was 11.1. What should be the correct answer?
一位同学在做一道一位小数减法题时，把减数个位上的1看成7，把减数十分位上的7看成1，结果得出差是11.1．正确答案应是几？
<gadget id="calculator">11.1 + 7.1</gadget>
<output>18.2</output>

<gadget id="calculator">18.2 - 1.7</gadget>
<output>16.5</output>

<result>16.5</result>