Respuesta :
We are given here the individual costs of DVD and CD as well as the total sales and the number of items sold on one day. To solve the number of DVDs and CDs sold each, we devise two independent linear equations:
(1) x + y = 39
(2) 4x + 7y = 204
x- number of DVDs; y - number of CDs
solving, x= 23 DVDs
Here's what we know:
D = 2C (A DVD has the same cost as 2 CDs)
2D + 2C = 45
Since we have a value for D, we can put that into our equation:
2(2C) + 2C = 45
4C + 2C = 45
6C = 45
C = 7.50
So a CD costs $7.50
D = 2C (A DVD has the same cost as 2 CDs)
2D + 2C = 45
Since we have a value for D, we can put that into our equation:
2(2C) + 2C = 45
4C + 2C = 45
6C = 45
C = 7.50
So a CD costs $7.50