When calculating a subtraction problem, Xiaoli wrote the 3 in the subtracted tens place as 6, and the 7 in the ones place as 9, and the calculation result was 45. What should be the correct result.
在计算一道减法题时，小丽把被减数十位上的3写成了6，个位上的7写成了9，这样计算的结果是45．正确的结果应该是多少．
<gadget id="calculator">9 - 7</gadget>
<output>2</output>

<gadget id="calculator">60 - 30</gadget>
<output>30</output>

<gadget id="calculator">45 - 2 - 30</gadget>
<output>13</output>

<result>13</result>