There are 5 red balls and 3 blue balls in an opaque box, and how many blue balls are put in, the probability of touching the red balls and blue balls is equal.
一个不透明的箱子里有5个红球和3个蓝球，再放入多少个蓝球，摸到红球和蓝球的可能性相等．
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<result>2</result>