Girls accounted for (7/12) of a science and technology invention interest group, and 15 girls were transferred later. At this time, girls accounted for the total number (3/5). How many boys are there in this interest group?
某科技发明兴趣小组中女生占(7/12)，后来又转来了15名女生，这时女生占总人数的(3/5)，这个兴趣小组男生有多少人？
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">12 - 7</gadget>
<output>5</output>

<gadget id="calculator">7 / 5</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">(3/2) - (7/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">15 / (1/10)</gadget>
<output>150</output>

<result>150</result>