box contains the same number of red and white balls. Take out 6 red balls and 4 white balls each time. After taking several times, the red balls are just taken out, and there are still 10 white balls. How many red balls are there in the box?
盒子里装有同样数量的红球和白球．每次取出6个红球和4个白球，取了若干次以后，红球正好取完，白球还有10个．盒子里原来有红球多少个．
<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">6 * 5</gadget>
<output>30</output>

<result>30</result>