Xiaoliang got 18 questions right and 2 questions wrong. What is Xiaoliang's correct rate for this assignment?
小亮做对了18道的题，做错了2道题，小亮这次作业的正确率是多少．
<gadget id="calculator">18 + 2</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>