There are several children in the big class of the kindergarten, among which boys accounted for (5/12), and later 6 boys were transferred, and at this time boys just accounted for (1/2) of the whole class. How many boys are there in this class?
幼儿园大班有若干个小朋友，其中男生占(5/12)，后来又转来了6个男生，这时男生正好占全班人数的(1/2)．这个班现有男生多少人．
<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<gadget id="calculator">1 / 1</gadget>
<output>1</output>

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

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">1 - (5/7)</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">6 / (2/7)</gadget>
<output>21</output>

<gadget id="calculator">21 * (5/7)</gadget>
<output>15</output>

<result>15</result>