To determine the cost of 18 CDs when we know that 12 CDs cost [tex]$30, we need to follow a step-by-step approach:
1. Determine the cost per CD:
- We know that the total cost for 12 CDs is $[/tex]30.
- Therefore, we calculate the cost per CD by dividing the total cost by the number of CDs.
[tex]\[
\text{Cost per CD} = \frac{30}{12} = 2.5
\][/tex]
So, the cost per CD is [tex]$2.50.
2. Calculate the total cost for 18 CDs:
- We now know each CD costs $[/tex]2.50.
- To find the total cost for 18 CDs, we multiply the cost per CD by the number of CDs.
[tex]\[
\text{Total cost for 18 CDs} = 2.5 \times 18
\][/tex]
- Multiplying these together, we get:
[tex]\[
\text{Total cost for 18 CDs} = 45.0
\][/tex]
Thus, the total cost for 18 CDs is $45.00.
