There are the same number of red balls and white balls in the box. Take out 5 red balls and 2 white balls from the box each time. After several times, the red balls are just taken out, and there are 12 white balls left in the box. How many white balls are there in the box? indivual.
箱子里有相同数量的红球、白球，每次从箱子里取出红球5个和白球2个，若干次后红球刚好取完，箱子里还剩下白球12个，原来箱子里有白球多少个．
<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">8 + 12</gadget>
<output>20</output>

<result>20</result>