You're buying gifts for 10 people. You decide to buy each person a CD or DVD. CD costs $12. DVD costs $20. Let c= the number of CD's you decide to buy. What is an expression in terms of c for the number of DVD's you buy? What is an expression in terms of c for the cost of the CD's? For the cost of DVD's? Write & simplify an expression in terms of c for the total cost of all the gifts you buy. What properties of real numbers did you use to simplify the expression?

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