A truck and a passenger car depart from A and B oppositely at the same time. The passenger car travels 50 kilometers per hour, and the distance traveled by the truck per hour is (4/5) that of the passenger car. After (7/9) hours, the two cars travel meet. How many kilometers are there between A and B?
一辆货车和一辆客车同时从A、B两地相对开出，客车每小时行50千米，货车每小时行的路程是客车的(4/5)，经过(7/9)小时两车相遇．A、B两地相距多少千米？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">50 * (4/5)</gadget>
<output>40</output>

<gadget id="calculator">40 + 50</gadget>
<output>90</output>

<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">90 * (7/9)</gadget>
<output>70</output>

<result>70</result>