If $26 represents the cost of the 5 used CDs, than your formula would be "26+4x" ,x being the amount of extra CDs you purchase.
The number CDs minus 5 is our x value, because the first 5 are the used CDs bundled into the $26 group.
26+4(6-5)
26+4(1)
26+4
30
6 CDs would cost $30
The formula for this is

. Filling in accordingly,

. This simplifies to

and 36=6x. Therefore, x = 6 so the bases are 6 and 12.
1/2 (6x - 10) + 10 = 5x - 13
(6x/2) - (10/2) + 10 = 5x - 13
3x - 5 + 10 = 5x - 13
3x - 5x = -13 + 5 - 10
-2x = -18
x = -18 / -2
x = 9
D.) x = 9
Answer:
20:5 - If you're going to simplify it, do 20/5 which is 4/1.
Step-by-step explanation: