total of 310 people in the fifth and sixth grades participated in the mathematics competition. It is known that (3/8) the number of the sixth grade is equal to (2/5) the number of the fifth grade. How many people in the fifth grade participated in the mathematics competition?
五年级和六年级共有310人参加数学竞赛，已知六年级人数的(3/8)等于五年级人数的(2/5)，五年级参加数学竞赛的有多少人？
<gadget id="calculator">15 + 16</gadget>
<output>31</output>

<gadget id="calculator">15 / 31</gadget>
<output>15/31 = around 0.483871</output>

<gadget id="calculator">310 * (15/31)</gadget>
<output>150</output>

<result>150</result>