In a math test, 8 of the 50 students in the class did not achieve excellence. Please calculate the excellent rate of the math scores of the whole class this time?
一次数学测试中，全班50人中有8人未达到优秀，请你算一算这次全班数学成绩的优秀率是多少？
<gadget id="calculator">50 - 8</gadget>
<output>42</output>

<gadget id="calculator">42 / 50</gadget>
<output>21/25 = around 0.84</output>

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

<gadget id="calculator">(21/25) * 1</gadget>
<output>21/25 = around 0.84</output>

<result>21/25 = around 0.84</result>