Among the students participating in various interest groups in the school, 70 students are not from the calligraphy group, and 85 are not from the art group. There are 135 students in the calligraphy group and the art group. How many people participate in the calligraphy group?
参加学校各类兴趣小组的学生中，有70人不是书法组的，有85人不是美术组的，书法组和美术组共有135人，参加书法组的有多少人？
<gadget id="calculator">85 - 70</gadget>
<output>15</output>

<gadget id="calculator">135 + 15</gadget>
<output>150</output>

<gadget id="calculator">150 / 2</gadget>
<output>75</output>

<result>75</result>