The school organized a total of 315 children in grades 3, 4, and 5 to participate in the spring outing. In order to distinguish students of each grade, children in grade 3 were required to wear white hats, children in grade 4 to wear red hats, and children in grade 5 to wear yellow hats. The unit price of the white hat is 1.5 yuan, the unit price of the red hat is 2.0 yuan, and the unit price of the yellow hat is 3.0 yuan. If the money used to buy the hats of the three colors is the same, how many third-grade children will participate in the spring outing?
学校组织三、四、五年级共315名小朋友参加春游，为了能区分每个年级的同学，要求三年级的小朋友戴白帽子，四年级的小朋友戴红帽子，五年级的小朋友戴黄帽子．白帽子的单价是1.5元，红帽子的单价是2.0元，黄帽子的单价是3.0元，如果买三种颜色的帽子所用的钱是一样的，那么，参加春游的三年级小朋友有多少人．
<gadget id="calculator">2 + 3 + 4</gadget>
<output>9</output>

<gadget id="calculator">315 / 9</gadget>
<output>35</output>

<gadget id="calculator">35 * 4</gadget>
<output>140</output>

<result>140</result>