The passenger car drives from A to B, and the truck drives from B to A. The passenger car is 12 kilometers longer than the truck per hour, and they meet after 4 hours. After meeting, the two cars continue to move forward in the original direction, and after another 3 hours the bus arrives at point B. How far is the truck from point B at this time?
客车从甲地开往开乙地，货车从乙地开往甲地，每小时客车比货车多得12千米，经过4小时相遇．相遇后，两车继续按原方向前进，又经过3小时客车到达乙地，这时货车离乙地多少米？
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">12 * 7</gadget>
<output>84</output>

<result>84</result>