There are 7 peaches, and each peach has a number on it. Xiao Ming takes two whose sum is 15, Xiao Li takes two whose sum is 9, Xiao Hong takes away two whose sum is 6, and there is one remaining. Please circle it.
有7个桃子，每个桃子上有1个数字，小明拿走和是15的两个，小力拿走和是9的两个，小红拿走差是6的两个，还剩一个，请把它圈出来．
<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<result>6</result>