Need help please.

[annarose]

You are buying gifts for 10 people. You decide to buy each person either a CD or a DVD. A CD costs $12 and a DVD costs $20.

A. Let c = the number of CDs you decide to buy. What is an expression in terms of c for the number of DVDs you buy.


B. What is an expression in terms of c for the cost of the CDs? For the cost of the DVDs?


C. Write and 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?

What I came up with:
A. 20c
B. ???
C. ???

Let me know if I got something wrong.
Thanks so much,
AnnaRose. [x

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[annarose]

You are buying gifts for 10 people. You decide to buy each person either a CD or a DVD. A CD costs $12 and a DVD costs $20.
A. Let c = the number of CDs you decide to buy. What is an expression in terms of c for the number of DVDs you buy.
Expression: 10-c

B. What is an expression in terms of c for the cost of the CDs? For the cost of the DVDs?
The cost of CDs is 12c. And the cost of the DVDs is 20(10-c).

C. Write and 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?

12c + 20(10 - c)
12c + 200 - 20c
-8c + 200

well is this right?

 

[Mrspi]

You are buying gifts for 10 people. You decide to buy each person either a CD or a DVD. A CD costs $12 and a DVD costs $20.
A. Let c = the number of CDs you decide to buy. What is an expression in terms of c for the number of DVDs you buy.
Expression: 10-c

B. What is an expression in terms of c for the cost of the CDs? For the cost of the DVDs?
The cost of CDs is 12c. And the cost of the DVDs is 20(10-c).

C. Write and 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?

12c + 20(10 - c)
12c + 200 - 20c
-8c + 200

well is this right?

Your answers look fine...but you still have one thing left to do. Notice that part C asks "what properties of real numbers did you use to simplify the expression?"