The boys in Class 1 of the sixth grade account for 2/5 of the whole class, and there are 18 girls. How many boys are there?
六年级1班的男生占全班人数的(2/5)，女生有18人．男生有多少人？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">18 / (3/5)</gadget>
<output>30</output>

<gadget id="calculator">30 * (2/5)</gadget>
<output>12</output>

<result>12</result>