Cars A and B meet each other after driving in opposite directions for 4 hours. The speed of car A is 15 kilometers faster than that of car B. The ratio of their speeds is 5:4. What is the distance in kilometers between the two places?
A，B两车从两地反向开车4小时候相遇，A车速度比B车速度快15千米，它们速度之比是5：4，两地之间的距离是多少千米？
<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">15 * 1 * 9</gadget>
<output>135</output>

<gadget id="calculator">135 * 4</gadget>
<output>540</output>

<result>540</result>