Cars A and B start from places A and B at the same time and drive towards each other. The speed of car A is 50 km/h, and the speed of car B is 70 km/h. After 3 hours, the two cars meet on the way. How many kilometers are there between A and B?
甲、乙两车从A、B两地同时出发，相向而行，甲车的速度是50千米/时，乙车的速度是70千米/时，经过3小时两车在途中相遇．A、B两地相距多少千米？
<gadget id="calculator">50 + 70</gadget>
<output>120</output>

<gadget id="calculator">120 * 3</gadget>
<output>360</output>

<result>360</result>