A primary school in Tangshan City organized a "Little Scientist" registration activity. The fourth-grade students responded positively. Among them, 35 people signed up for the fun physics group, 46 people signed up for the fun chemistry group, and 7 students signed up for both groups. How many students in the fourth grade signed up for the fun physics group and the fun chemistry group?
唐山市某小学组织"小小科学家"报名活动．四年级同学积极响应，其中报名趣味物理小组的有35人，报名趣味化学小组的有46人，有7名同学两个小组都报了．四年级一共有多少名同学报名趣味物理小组和趣味化学小组？
<gadget id="calculator">46 - 7</gadget>
<output>39</output>

<gadget id="calculator">35 + 39</gadget>
<output>74</output>

<result>74</result>