How many CDs did she purchase?

Question

At a local electronic store, CDs were on sale. Some were priced at 14$ and some were priced at 12$. Sabrina bought 9 CDs and spent a total of 114$. How many CDs did she purchase?

Answer 1

How many at each price dd she purchase might be want you really want. If you want how many CDs were purchased that is in the problem, 9

 

Let's assume it's the first case

 

 

Let X = cheaper CD

Let Y = more expensive CD

 

X + Y = 9  (#1)

 

12X + 14Y = 114 (#2)

 

We can solve this system by using elimination

 

We will multiply equation #1 by 12

 

12X + 12Y = 108  (#3)

12X + 14Y = 114 (#2)

 

Now subtract #3 from #2

 

2Y = 6

 

Now divide by 2

 

Y = 3

 

Sabrina bought 3 of the more expensice CDs and thus bought 9 - 3 or 6 of the cheaper CDS