You can predict that it's odd because the end of the 2 numbers is 1 and 1 x 1 is 1 and one is an odd number. (answer is odd)
Well, he could of spent $24
And we know he spent $4 on the magazine So subtract $4 from $24 to get $20
And $20/5(the composition books) = $4
So the Composition books also costed $4
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