Hongqi Primary School has two interest groups of science and technology and writing. There are 45 people participating in the science and technology interest group, 34 people participating in the writing interest group, and 12 people participating in both groups. How many students are there in the two interest groups?
红旗小学有科技和写作两个兴趣小组，参加科技兴趣小组的有45人，参加写作兴趣小组的有34人，两个小组都参加的有12人，两个兴趣小组共有学生多少人？
<gadget id="calculator">34 - 12</gadget>
<output>22</output>

<gadget id="calculator">45 + 22</gadget>
<output>67</output>

<result>67</result>