The passenger car and the truck travel in opposite directions from the midpoint of A and B at the same time. After 4 hours, the bus arrives at A, and the truck is 40 kilometers away from B. The ratio of the speed of the truck to the speed of the passenger car is 3:4. How many kilometers are there between A and B?
客车和货车同时从甲乙两地的中点向相反方向行驶，4小时后客车到达甲地，货车离乙地还有40千米，已知货车速度与客车速度的比为3：4．甲乙两地相距多少千米？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">40 / (1/4)</gadget>
<output>160</output>

<gadget id="calculator">160 * 2</gadget>
<output>320</output>

<result>320</result>