The taxi fare in a certain city is stipulated as follows: within 3 kilometers, the starting price is 8 yuan; if it exceeds 3 kilometers, the excess part is within 4 kilometers, 1.4 yuan per kilometer; after 4 kilometers, it is 2.1 yuan per kilometer. Yuan. Uncle Wang's taxi fare is 22 yuan. How many kilometers did the taxi travel?
某市的士费是这样规定的：3千米以内为起步价8元；超过3千米的，超过部分在4千米以内，每千米1.4元；超过4千米以后的每千米2.1元．王叔叔一次搭的士的车费为22元，的士行驶了多少千米？
<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>