Fourth grade students participate in interest group activities. There are 240 people in the art group, 30 people less than three times the number of calligraphy group. How many people are there in the calligraphy group?
四年级学生参加兴趣小组活动，美术组240人，比书法组人数的3倍少30人，书法组有多少人？
<gadget id="calculator">240 + 30</gadget>
<output>270</output>

<gadget id="calculator">270 / 3</gadget>
<output>90</output>

<result>90</result>