In one activity, 12 balls of different colors should be arranged in a circle along the circle drawn on the ground, each ball should be placed on the circle, and the arc between each two balls is 2 meters long, Counting by the hour hand, the red ball is the first, and the basketball is the ninth. What is the length of the arc between the red ball and the basketball?
在一次活动中，要将12个颜色各异的球沿着画在地上的圆圈排成一圈，每个球都放在圆圈上，且每两个球之间的圆弧长2米，顺时针数，红球排第一个，篮球排第九个．那么，红球和篮球间的圆弧长多少米．
<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<gadget id="calculator">9 - 1</gadget>
<output>8</output>

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

<gadget id="calculator">24 - 16</gadget>
<output>8</output>

<result>8</result>