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Part III

Answer all 3 questions in this part. Each correct answer will receive 3 credits. Clearly

indicate the necessary steps, including appropriate formula substitutions, diagrams, graphs,

charts, etc. For all questions in this part, a correct numerical answer with no work shown will

receive only

credit. All answers should be written in pen, except for graphs and drawings,

which should be done in pencil. [9]

A DVD costs twice as much as a music CD. Jack buys 2 DVDs and 2 CDs and spends $45.

Determine how much one CD costs, in dollars. [Only an algebraic solution can receive full credit.]

Verified Answer :

Cost of CD = x
Cost of DVD = 2x

2 DVDs and 2 CDs for $45.

2(2x) +  2x = 45
4x + 2x = 45
6x = 45
6x/6 = 45/6
x = 7.50 * cost of CD

Cost of DVD = 2x = 2 * 7.50 = $
15

To check:

2(2x) + 2x = 45
2(2(7.5)) + 2(7.50) = 45
2(15) + 15 = 45
30 + 15 = 45
45 = 45