Question
Eric bought the same number of notebooks and files. The total cost of 4 notebooks and 1 file was $31. The total cost of 1 notebook and 4 files was $19. He spent a total of $70. How many notebooks did Eric buy?
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Eric bought the same number of notebooks and files. The total cost of 4 notebooks and 1 file was $31. The total cost of 1 notebook and 4 files was $19. He spent a total of $70. How many notebooks did Eric buy?