passenger car and a truck are traveling towards each other from A and B at the same time. When they meet, the truck is still 40km away from the midpoint. It is known that the speed ratio of the truck to the passenger car is 3:4. How many kilometers are the distance between A and B?
客车、货车同时从A、B两地相向而行，相遇时，货车离中点还有40km，已知货车与客车的速度比是3：4，A、B两地相距多少千米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(1/2) - (3/7)</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">40 / (1/14)</gadget>
<output>560</output>

<result>560</result>