Li Ming is going to the library to read a book. For the first 15 minutes, he walks 45 meters per minute. Later, he speeds up and walks 55 meters per minute. After 10 minutes, he arrives at the library. How many meters per minute does Li Ming walk on average?
李明要去图书馆看书，前15分钟每分钟走45米，后来加快速度，每分钟走55米，10分钟后到达图书馆，李明平均每分钟走多少米？
<gadget id="calculator">45 * 15</gadget>
<output>675</output>

<gadget id="calculator">55 * 10</gadget>
<output>550</output>

<gadget id="calculator">675 + 550</gadget>
<output>1_225</output>

<gadget id="calculator">15 + 10</gadget>
<output>25</output>

<gadget id="calculator">1_225 / 25</gadget>
<output>49</output>

<result>49</result>