Question

mr a can buy six cds and 3 videos for $163.17 or nine cd's and two vids for $200.53.what is the cost of 1 cd?

Answer 1

let x and y be the cost 1CD and 1 video respectively
6x + 3y = 163.17 => y = 54.39 - 2x -(1)
9x +2y = 200.53 -(2)
Put (1) into (2) and solve for x. There you'll get your answer. Can you do it?

Answer 2

6C+3V=163.17

9C+2V=200.53

C=CD
V=VIDEO

6C=163.17-3V

C=(163.17)/(6)-(3V)/(6)
substitute to the second equation.... and you'll have..

9C+2V=200.53

\[\Large 9\left(\frac{163.17}{6}-\frac{3V}{6}\right)+2V=200.53\]

Go on...