Answer:
Explanation:
Let x represent the number of large vases Gretchen bought. Here total cost was then ...
11x +7(18-x) = 142
4x + 126 = 142 . . . . .simplify
4x = 16 . . . . . . . . . . . subtract 126
x = 4 . . . . . . . . . . . . divide by 4: number of large vases
18-x = 14 . . . . . . . . . number of small vases
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Gretchen bought 4 large vases and 14 small vases.