There are 4 red balls and 6 yellow balls in the pocket. If you touch any one of them, the probability of touching a red ball is ((())/(())); if the probability of touching a red ball is 50 %, how many yellow balls should be reduced.
口袋中有4个红球和6个黄球，从中任意摸一个，摸到红球的可能性是((())/(()))；如果要使摸到红球的可能性为50%，应减少多少个黄球．
<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<result>2</result>