Students from a certain school are conducting camping training, and the four command posts A, B, C, and D are respectively set up on a straight line in sequence. It is known that the distance from A to D is 16 kilometers, and the distance between B and C is 4 kilometers. Correspondent A starts from A to D and walks 3 kilometers per hour. Correspondent B starts from D to A and walks 2 kilometers per hour. , after the two start at the same time, when A walks to C, B just walks to B. Find the distance between the headquarters A and B.
某校同学进行野营训练，A、B、C、D四个指挥部按顺序分别设在一条直线上．已知从A到D的距离是16千米，B、C相距4千米，甲通信员从A出发到D，每小时走3千米，乙通信员从D出发到A，每小时走2千米，两人同时出发后，当甲走到C时，乙正好走到B．求A、B两指挥部的距离．
<gadget id="calculator">16 + 4</gadget>
<output>20</output>

<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">16 - 8</gadget>
<output>8</output>

<result>8</result>