Two people, A and B, start from A and B at the same time and drive towards each other; after meeting, A continues to drive to B, and B has two choices: If B drives to A. Then when A arrives at B, B is 45 kilometers away from A; if B immediately turns around and drives to B at a speed of Yuan, then when A arrives at B, B is 15 kilometers away from B. Question: How many kilometers are there between A and B?
甲、乙两人分别从A、B两地同时驾车出发相向而行；相遇后，甲继续驶向B地，乙有两种选择：若乙驶向A地．则当甲到达B地时，乙距离A地45千米；若乙立即掉头以元速度驶向B地，则当甲地到达B地时，乙距离B地15千米．问：A、B两地相距多少千米？
<gadget id="calculator">45 - 15</gadget>
<output>30</output>

<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">60 + 30</gadget>
<output>90</output>

<result>90</result>