The school held a singing competition. The number of students in the sixth grade accounted for 2/7 of the whole grade. Later, 5 students participated in the competition. At this time, the ratio of the number of participants to the number of non-participants was 5:9. How many students were there in the sixth grade? ?
学校举行歌咏比赛，六年级参加的人数占全年级人数的(2/7)，后来又有5名学生参加比赛，这时参赛人数与没参赛人数的比是5：9，六年级有多少人？
<gadget id="calculator">5 + 9</gadget>
<output>14</output>

<gadget id="calculator">5 / 14</gadget>
<output>5/14 = around 0.357143</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(5/14) - (2/7)</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">5 / (1/14)</gadget>
<output>70</output>

<result>70</result>