The students are doing morning exercises, 36 students are lined up in the order of two girls and two boys, the first one is a girl, how many boys are there in this line?
同学们做早操，36个同学按两个女生、两个男生的顺序排成一列，第一个是女生，这列队伍中男生有多少人？
<gadget id="calculator">2 + 2</gadget>
<output>4</output>

<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>