Secretary Li printed a speech, first printed 1.8 hours, a total of 4,500 words were printed, and the number of words printed in the next 3.2 hours was 2.4 times that of the first 1.8 hours. How many words did Secretary Li print per hour on average?
李秘书打印一份发言稿，先打印1.8小时，一共打印了4500字，后3.2小时打印的字数是前1.8小时打印的2.4倍，李秘书后来平均每小时打印多少字？
<gadget id="calculator">2.4 / 3.2</gadget>
<output>0.75</output>

<gadget id="calculator">4_500 * 0.75</gadget>
<output>3_375</output>

<result>3_375</result>