The number of students in the art group of the school is the calligraphy group (4/5), and the ratio of the number of people in the art group to the mathematics group is 3:5. There are 30 people in the calligraphy group, how many people are there in the mathematics group?
学校美术组的人数是书法组的(4/5)，美术组人数与数学组的比是3：5．书法组有30人，数学组有多少人？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">5 / 3</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">30 * (4/5) * (5/3)</gadget>
<output>40</output>

<result>40</result>