Answer:
The number of books bought in each store would be 4 The amount spent will be the same in either store.
Explanation:
Comment
The question has to make the assumption that no matter how many books are bought from store 1, the shipping charge is 8 dollars. Otherwise there is no solution.
Givens
Book1: 10 and 8 dollars total for shipping
Book2: 12 dollars, no shipping costs.
Equation
12x = 10x + 8 Subtract 10x from both sides
Solution
12x - 10x = 10x - 10x + 8 Combine
2x = 8 Divide both sides by 2
2x/2 = 8/2
x = 4