A used book store is selling 3 records and 5 CDs for $60. You can also buy 6 records and 4 CDs for $80. Find the cost of one CD. Write the linear system that describes this situation.​

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  3r +5c = 60

  6r +4c = 80

Step-by-step explanation:

There are many aspects of "this situation" that could be described by equations. We are guessing that you want equations that will help you determine the costs of a record and a CD, assuming the costs are the same for each instance of the media.

Let r and c represent the costs of a record and a CD, respectively.

  3r +5c = 60 . . . . . . . the value of the first purchase

  6r +4c = 80 . . . . . . . the value of the second purchase

These equations comprise a linear system describing an aspect of the situation.

Comment on the question

The numbers make no sense, as the cost of a CD is $(6 2/3), the cost of a record is $(8 8/9).

ab will be equal to

d. it is a convex pentagon because it has five sides and none of the sides would extend into the inside of the polygon.

step-by-step explanation: