SOLUTION: Book store sold 40cds & videos the 1st week at $4 per cd $6per videos. Sales for both total $180. Write a system of equations to represent the situation and graph the system if eq

Algebra ->  Graphs -> SOLUTION: Book store sold 40cds & videos the 1st week at $4 per cd $6per videos. Sales for both total $180. Write a system of equations to represent the situation and graph the system if eq      Log On


   

Question 840818: Book store sold 40cds & videos the 1st week at $4 per cd $6per videos. Sales for both total $180. Write a system of equations to represent the situation and graph the system if equations.
Thank you
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
d for count of disks
v for count of videos

Account for the count: d+v=40
Account for sales revenue: 4d+6v=180

The revenue equation should be simplified, dividing left and right by 2:
2d+3v=90

Elimination Method on THIS system would be most convenient:
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2d+3v=90
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d+v=40
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...
highlight%28v=10%29, done in head; I used multiplication of the "40" equation by 2 and subtracted from the "90" equation.
highlight%28d=30%29