In a subtraction problem, Maomao mistook the 9 in the tenth place of the subtrahend as 6, and the 6 in the subtrahend ones place as 9, and the result difference was 3.87. What should be the correct result?
一道减法题，毛毛把被减数十分位上的9错看成6，把减数个位上的6错看成9，结果差是3.87，正确的结果应当是多少．
<gadget id="calculator">90 - 60</gadget>
<output>30</output>

<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<gadget id="calculator">30 + 3</gadget>
<output>33</output>

<gadget id="calculator">3.87 + 33</gadget>
<output>36.87</output>

<result>36.87</result>