Answer:
c = 21
Explanation:
**I assume that side WX in my diagram (attached as an image below) is the value of C that we're looking for. ALSO, the sizes and lengths of the parallelograms are NOT to scale.**
If two parallelograms are similar, that means the lengths of the corresponding sides have EQUAL ratios.
PL corresponds with WZ. To get from 15 to 45, you would multiply 15 by 3, so the ratio of the legnths of the corresponding sides between these two parallelograms is 1:3.
With that in mind, we can apply this ratio to find WX.
We know that AP has a length of 7, so we will multiply that by 3, getting a value of 21, and 7:21 ratio is the same as 1:3.
c = 21
Hope this helps (●'◡'●)