The box contains the same number of red and yellow balls. Take out 5 red balls and 3 yellow balls each time. After taking several times, the red balls are just taken out, and there are still 12 yellow balls. How many balls are there in the box?
盒子里装有同样数量的红球和黄球．每次取出5个红球和3个黄球，取了若干次后红球正好取完，黄球还有12个，盒子里一共有多少个球．
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">18 + 12 + 18 + 12</gadget>
<output>60</output>

<result>60</result>