Answer: 28 cookies
Explanation:
We have to add up the number of cookies distributed and subtract it from the total amount of cookies he brought in order to find out how many cookies he has left over.
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First class
For the first class with 28 students, Mr. Walker distributed 28 cookies.
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Second Class
There are 29 people in the second class, which has 27 students and 2 teachers.
Mr. Walker then gave out 29 cookies.
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Office Staff and Custodians
Mr. Walker left 10 for the office staff, 5 for the custodians, which is a total of 10 + 5 = 15.
So, Mr. Walker distributed 15 cookies.
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Finding the answer
We add up the number of cookies distributed to figure out how many cookies he had leftover:
28 + 29 + 15 = 72.
This gets subtracted from the total number of cookies brought by him:
100 - 72 = 28.
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Answer
Therefore, after giving cookies to the two classes, the office staff, and the custodians, Mr. Walker had 28 cookies left over.