Two people A and B start from A and B at the same time and walk toward each other. They meet for the first time at a distance of 50 meters from A. Back on the same road, the two met for the second time at a place 20 meters away from B. What is the distance between A and B in meters?
甲、乙两人同时从A、B两地出发相向而行，两人在离A地50米处第一次相遇，相遇后两人继续以原速度前进，并且在各自到达对方出发点后立即没原路返回，途中两人在距B地20米处第二次相遇．问A、B两地相距的路程是多少米？
<gadget id="calculator">50 * 3</gadget>
<output>150</output>

<gadget id="calculator">150 - 20</gadget>
<output>130</output>

<result>130</result>