Xiao Ming did 10 questions yesterday and got 9 right; today he did 10 questions and got 1 wrong. What is Xiao Ming's correct rate of doing the questions in the past two days?
小明昨天做了10道题，对了9道；今天做了10道，错了1题．小明这两天做题的正确率是多少．
<gadget id="calculator">9 + 9</gadget>
<output>18</output>

<gadget id="calculator">10 + 10</gadget>
<output>20</output>

<gadget id="calculator">18 / 20</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(9/10) * 1</gadget>
<output>9/10 = around 0.9</output>

<result>9/10 = around 0.9</result>