Question

Best Buy was having a special in all their tapes and CDs. Jane was able to buy 4 tapes and 3 CDs for $54. Larry bought 6 CDs and 3 tapes for $78. How much did a CD cost on special?

Answer 1

First we put the data in equations:

let Tapes are denoted with T and CDs are denoted with C just for the better understanding.

4T+ 3C= $54 ----equation 1

3T+ 6C= $78 ----equation 2

(multiplying by 2 in equation 1), then we get

8T+ 6C= $108 ----equation 3

(subtracting equation 2 from equation 3), then we get

5T= $30

T = $ 6

by putting T's value in equation 1, we get

4(6)+ 3C= $54

24+ 3C= $54

3C= $(54-24)

3C= $30

C= $10

Thus, a CD cost on special is $10