Two cars A and B are traveling toward each other from the east and west cities at the same time. Car A travels 50 kilometers per hour, and car B travels 70 kilometers per hour. The two cars meet at a distance of 15 kilometers from the midpoint of the two cities. How many kilometers is the distance between the east and west cities?
甲乙两车同时从东西两城相向而行，甲车每小时行50千米，乙车每小时行70千米，两车在距两城中点15千米处相遇．求东西两城相距多少千米？
<gadget id="calculator">70 + 50</gadget>
<output>120</output>

<gadget id="calculator">70 - 50</gadget>
<output>20</output>

<gadget id="calculator">2 / 20</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">15 * (1/10)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">120 * (3/2)</gadget>
<output>180</output>

<result>180</result>