A taxi in a city charges 8 yuan within 3km; over 3km, 1.5 yuan per kilometer (less than 1km is calculated as 1km). Dad traveled 16.8km, how much does he need to pay the driver?
某市的出租车3km以内收费8元；超过3km，每千米1.5元(不足1km按1km计算)．爸爸乘坐了16.8km，需要付给司机师傅多少钱？
<gadget id="calculator">16.8 - 3</gadget>
<output>13.8</output>

<gadget id="calculator">1.5 * 13.8</gadget>
<output>20.7</output>

<gadget id="calculator">8 + 20.7</gadget>
<output>28.7</output>

<result>28.7</result>