the music department of a local store orders 4 times as many Rock CDs as jazz CDs.
If the department orders a total of 550 CDs, how many of each type of CD was ordered?
Let R be the number of rock CDs and J be the number of jazz CDs. We know that R = 4J and R + J = 550.
Substituting the first equation into the second equation, we get 4J + J = 550
Combining like terms, we get 5J = 550
Dividing both sides by 5, we get J = 110
Now that we know J, we can find R: R = 4J = 4 * 110 = 440
The store orders 440 Rock CDs and 110 Jazz CDs.