The taxi regulations in a certain city are as follows: 8 yuan within 3 kilometers, 1.4 yuan per kilometer for the excess part within 4 kilometers, and 2.1 yuan per kilometer for more than 4 kilometers. The total fare was 22 yuan. Do the math, how many kilometers did Li Feng travel by car?
某市的出租车是这样规定的：3千米以内8元，超过部分在4千米以内，每千米1.4元，超过4千米以外的每千米2.1元，李丰乘出租车办事，共花车费22元，算一算，李丰乘车走了多少千米？
<gadget id="calculator">1.4 * 4</gadget>
<output>5.6</output>

<gadget id="calculator">22 - 8 - 5.6</gadget>
<output>8.4</output>

<gadget id="calculator">8.4 / 2.1</gadget>
<output>4</output>

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

<gadget id="calculator">4 + 7</gadget>
<output>11</output>

<result>11</result>