There are several balls in the bag, among which the red balls account for (5/12), and then 6 red balls are put into the bag, at this time, the red balls account for (1/2) of the total, how many balls are there in the bag now?
袋里有若干个球，其中红球占(5/12)，后来又往袋里放了6个红球，这时红球占总数的(1/2)，现在袋里有多少个球．
<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 * 2</gadget>
<output>42</output>

<result>42</result>