Car A travels 45 kilometers per hour, and car B travels 60 kilometers per hour. Two cars set off from A and B at the same time and drive toward each other. Car A arrives at B 4 hours after meeting. How many kilometers are there between A and B?
甲车每小时行45千米，乙车每小时行60千米．两车分别从A、B两地同时出发，相向而行，相遇后4小时甲车到达B地，A、B两地相距多少千米？
<gadget id="calculator">4 / 60</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">45 + 60</gadget>
<output>105</output>

<gadget id="calculator">45 * (1/15) * 105</gadget>
<output>315</output>

<result>315</result>