Question 1099148
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Let A be the number of activity books.

Then the number of story books is (12-A).

The "money" equation is

2A + 9*(12-A) = 45    dollars.   (Counting A-books at 2 dollars and story-books at 9 dollars)

Simplify and solve for A:

2A + 108 - 9A = 45  ====>  -7A = 45 - 108 = - 63   ====>  A = {{{(-63)/(-7)}}} = 9.


<U>Answer</U>.  Chris purchased 9 activity books and 12-9 = 3 story books.
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