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David buys 2 DVDs and 2 CDs in a shop and in total they cost £18.
Ellie buys 3 DVDs and 2 CDs in the same shop and they cost £22.
Form two equations and solve to find the cost of each DVD and each CD.

Respuesta :

Kittenpeeps31

Answer: Down below

Step-by-step explanation:

Let x be the cost for the DVD's

Let y be the cost of the CD's

Equations :

2x + 2y = 18   OR   y = (18 - 2x)/2

3x + 2y = 22

Substitution :

3x + 2[(18 - 2)/2] = 22

3x + 2(16/2) = 22

3x + 2(8) = 22

3x + 16 = 22

3x = 22 - 16

3x = 6

x = 6/3

x = 2

that's just the cost of the DVD though. now to find the CD's cost

Cost of CD's :

y = (18 - 2x)/2

y = [18 - 2(2)]/2

y = (18 - 4)/2

y = 14/2

y = 7

therefore 1 CD costs 7 pounds and 1 DVD costs 2 pounds

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