Taxi charges in Wuhan are as follows: the starting fare is 10 yuan (within 3 kilometers), and 1.8 yuan per kilometer over 3 kilometers (calculated as 1 kilometer for less than 1 kilometer). How much does it cost for a family of three to take a taxi for an autumn tour 9 kilometers away?
武汉市出租车收费标准如下：起步价为10元(3千米以内)，超过3千米每千米1.8元(不足1千米的按1千米计算)．明明一家三口乘出租车去9千米外秋游，需要付多少钱？
<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<gadget id="calculator">6 * 1.8</gadget>
<output>10.8</output>

<gadget id="calculator">10.8 + 10</gadget>
<output>20.8</output>

<result>20.8</result>