There are 252 students in the first day of Jiefang Middle School, girls accounted for (3/7), and some girls were transferred. At this time, girls accounted for the current total number (7/15). How many girls are transferred?
解放中学初一有学生252人，女生占(3/7)，又转来一些女生，这时女生占现在总人数的(7/15)，求转来几名女生？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (3/7)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">252 * (4/7)</gadget>
<output>144</output>

<gadget id="calculator">7 / 15</gadget>
<output>7/15 = around 0.466667</output>

<gadget id="calculator">1 - (7/15)</gadget>
<output>8/15 = around 0.533333</output>

<gadget id="calculator">144 / (8/15)</gadget>
<output>270</output>

<gadget id="calculator">270 - 252</gadget>
<output>18</output>

<result>18</result>