180 students in the fifth grade participated in the calligraphy competition, 20 won the first prize, 40 won the second prize, and the rest won the third prize. What percentage of the students who won the third prize accounted for all the participating students?
五年级180名同学进行书法比赛，获得一等奖的有20名，获得二等奖的有40名，其余的获三等奖．获三等奖的学生占全部参赛学生的几分之几？
<gadget id="calculator">180 - 20 - 40</gadget>
<output>120</output>

<gadget id="calculator">120 / 180</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>