Students in the third and fourth grades participated in the sports interest group activities. There were 109 people in the sports interest group, 78 people in the literature and art interest group, and 9 people from the right who participated in both. Ask: How many students in the third and fourth grades participated in the sports interest group people?
三四年级同学参加文体兴趣小组活动，参加体育兴趣小组的有109人，参加文艺兴趣小组的有78人，两项都参加的右9人，问：三四年级同学参加文体兴趣小组的共有多少人？
<gadget id="calculator">78 - 9</gadget>
<output>69</output>

<gadget id="calculator">109 + 69</gadget>
<output>178</output>

<result>178</result>