A math problem, 30 people in the class get it right and 10 people get it wrong, what is the correct rate?
一道数学题，全班30人做对，10人做错，正确率是多少．
<gadget id="calculator">30 + 10</gadget>
<output>40</output>

<gadget id="calculator">30 / 40</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(3/4) * 1</gadget>
<output>3/4 = around 0.75</output>

<result>3/4 = around 0.75</result>