One morning, Mr. Li walked 80 meters per minute from home to school, and arrived at school in 12 minutes. Later, he found that he forgot to bring a book, so he went home to pick up the book and rushed back to school. It took another 20 minutes. How many meters per minute did Mr. Li walk on average during his work this morning?
某日清晨，李老师从家到学校每分钟走80米，走了12分钟到达学校，后来发现忘带了一本书，于是回家取了书又赶回到了学校，又用了20分钟，李老师这天清晨上班的过程平均每分钟走多少米？
<gadget id="calculator">80 * 12 * 3</gadget>
<output>2_880</output>

<gadget id="calculator">12 + 20</gadget>
<output>32</output>

<gadget id="calculator">2_880 / 32</gadget>
<output>90</output>

<result>90</result>