Cars A and B are traveling toward each other from AB at the same time. When they meet, Car A is 50 kilometers away from B. The two vehicles continue to move forward, and when they reach AB, they return immediately. Car B was 30 kilometers away from place A when they met. How many kilometers are there between A and B?
甲乙两车从AB两地同时相向而行，相遇时甲车离B地50千米．两车继续前进，到达AB两地后，立即返回．相遇时乙车离A地30千米．甲乙两地相距多少千米．
<gadget id="calculator">50 * 3</gadget>
<output>150</output>

<gadget id="calculator">150 - 30</gadget>
<output>120</output>

<result>120</result>