Question 1072559
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Let n be that unknown number of grandchildren.


Then the number of cookies C = 4n +2, according to the first part of the condition.


At the same time,  C = 5n - 2, from the other part of the condition.


It gives you an equation


4n + 2 = 5n -2,


which gives you the solution  n = 4.


<U>Answer</U>.  The number of grandchildren is 4.

         The number of cookies is 18.
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Solved.