Wang Mazi went from A to B, and Li Si went from B to A. The two set off at the same time, and the distance between them was 13.5 kilometers after 2 hours; after 5 hours of departure, neither of them reached the destination, but they were still 13.5 kilometers apart. How many kilometers are there between A and B?
王麻子从甲地到乙地，李四从乙地到甲地．两人同时出发，2小时后相距13.5千米；出发5小时后，两人都未到达目的地，但还相距13.5千米．求甲乙两地相距多少千米？
<gadget id="calculator">13.5 + 13.5</gadget>
<output>27</output>

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

<gadget id="calculator">27 / 3</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<gadget id="calculator">18 + 13.5</gadget>
<output>31.5</output>

<result>31.5</result>