The starting price of a taxi in a certain city is 5 yuan (within 3 kilometers). More than 3 kilometers, an average of 2 yuan per kilometer. Xiaofan's family of three took a taxi to his grandfather's house and paid a total of 13 yuan. How far is the maximum distance between Xiaofan's house and grandpa's house? (The fare of 13 yuan includes the starting price of 5 yuan and the fare of the part exceeding 3 kilometers)
某市出租车起步价为5元(3千米以内)．超过3千米，平均每千米另加2元．小凡一家三口人乘出租车到爷爷家共付车费13元．小凡家离爷爷家最多有多远？(13元车费里面包括起步价5元和超过了3千米部分的车费哦)
<gadget id="calculator">13 - 5</gadget>
<output>8</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<result>7</result>