SOLUTION: Mary has a \$90 gift certificate for a book store where paperbacks cost \$9 and hardback books cost \$12. She must spend at least \$25 and no more than \$90 to use the gift certificate

Algebra ->  -> SOLUTION: Mary has a \$90 gift certificate for a book store where paperbacks cost \$9 and hardback books cost \$12. She must spend at least \$25 and no more than \$90 to use the gift certificate      Log On

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 Click here to see ALL problems on Linear-systems Question 128751: Mary has a \$90 gift certificate for a book store where paperbacks cost \$9 and hardback books cost \$12. She must spend at least \$25 and no more than \$90 to use the gift certificate. Write a system of inequalities to determine the formula for using the gift certificate. I came up with 9x + 12y is less than or equal to 90; and 9x + 12y is greater than or equal to 25. Is that correct? Answer by checkley71(8403)   (Show Source): You can put this solution on YOUR website!25<=9X+12Y<=90 THIS IS A SINGLE EQUATION FOR THIS PROBLEM.