A used book store also started selling used CDs and DVDs. In the first week, the store sold 40 used CDs and DVDs, at $6.00 per CD and $4.00 per DVD. The sales for both CDs and DVDs totaled $180.00. Write a system of equations to
represent this situation

6c + 4d = 180

c + d = 40

c represents the CDs and d represents the DVDs.

step-by-step explanation:

descending order means to order the polynomials from the term with the largest exponent to the term with the smallest exponent.  

therefore, the correct answer is d.  

to find the perimeter of the rectangle this is the expression:

x-9+x-9+3x-4+3x-4=138

if we simplify it:

8x-26=138

remember, 138 is what it all adds up to

the length is 11.5cm

the width is 57.5cm

the area is 661.25cm^2

the answers might not be correct use at own risk