Xiao Wang and Xiao Li start from A and B at the same time, and walk with their backs. Xiao Wang travels 4.8 kilometers per hour, and Xiao Li travels 4.4 kilometers per hour. After 2.5 hours, the distance between the two is 31.5 kilometers. Find A and B The distance between the two places.
小王、小李从甲、乙两地同时出发，背向而行，小王每小时行4.8千米，小李每小时行4.4千米，经过2.5小时，两人相距31.5千米，求甲、乙两地间的距离．
<gadget id="calculator">4.8 + 4.4</gadget>
<output>9.2</output>

<gadget id="calculator">9.2 * 2.5</gadget>
<output>23</output>

<gadget id="calculator">31.5 - 23</gadget>
<output>8.5</output>

<result>8.5</result>