box is filled with the same number of red balls and yellow balls, and 5 red balls and 3 yellow balls are taken out each time. After taking a few times, the red balls are gone, and there are 16 yellow balls left. How many red balls are there in the original box?
盒子里装有同样数目大的红球和黄球，每次取出5个红球和3个黄球．取了几次以后红球就没有了，黄球还剩16个，原来盒子有红球多少个．
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<result>40</result>