passenger car and a truck leave Lishui and Shanghai along the expressway at the same time, and the distance between the two cars is 154 kilometers after 1 hour. It is known that it takes 4 hours for a passenger car and 5 hours for a truck to complete the journey. How long is the expressway from Lishui to Shanghai in kilometers?
一辆客车和一辆货车分别从溧水和上海两地沿着高速公路同时相对开出，1小时后两车相距154千米．已知客车行完全程要4小时，货车行完全程要5小时，问溧水到上海的高速公路全长多少千米？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) + (1/5)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">1 - (9/20)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">154 / (11/20)</gadget>
<output>280</output>

<result>280</result>