Li Ming and Wang Yong rode bicycles opposite each other from counties A and B respectively, and Wang Yong started after Li Ming first rode 5 kilometers. It is known that Li Ming traveled 12 kilometers per hour, and Wang Yong traveled 15 kilometers per hour, and they met after 5 hours. How many kilometers are there between the towns of A and B?
李明和王勇两人分别从甲、乙两县城相对骑车而行，而王勇是在李明先骑出5千米后才出发的．已知李明每小时行12千米，王勇每小时行15千米，5小时后两人相遇．甲、乙两县城相距多少千米？
<gadget id="calculator">12 + 15</gadget>
<output>27</output>

<gadget id="calculator">27 * 5</gadget>
<output>135</output>

<gadget id="calculator">5 + 135</gadget>
<output>140</output>

<result>140</result>