When Xiaohong was calculating an addition problem, she mistakenly wrote 4.2 as 42, and the result was 49.7. What should be the correct result?
小红在计算一道加法题时，把4.2错写成了42，结果得49.7，正确的结果应是多少？
<gadget id="calculator">49.7 - 42</gadget>
<output>7.7</output>

<gadget id="calculator">7.7 + 4.2</gadget>
<output>11.9</output>

<result>11.9</result>