In a certain city, taxis charge 8 yuan within 3 kilometers, and an additional 1.8 yuan for every additional kilometer thereafter. Uncle Wang is 7 kilometers away from home to school, how much should he pay by taxi?
某市出租车规定3公里以内收费8元，之后每超出一公里多收1.8元．王叔叔从家到学校有7公里，坐出租车应付多少钱？
<gadget id="calculator">7 - 3</gadget>
<output>4</output>

<gadget id="calculator">1.8 * 4</gadget>
<output>7.2</output>

<gadget id="calculator">7.2 + 8</gadget>
<output>15.2</output>

<result>15.2</result>