When Xiao Hua did the subtraction calculation, she wrote "7" for the "2" in the subtracted tens digit, and the result was 419. What is the correct answer?
小花做减法计算时，把被减数十位上的"2写成"7"，结果是419，正确的答案是多少．
<gadget id="calculator">70 - 20</gadget>
<output>50</output>

<gadget id="calculator">419 - 50</gadget>
<output>369</output>

<result>369</result>