One side of a rectangle is 3 inches shorter than the other side, and the perimeter is 54 inches. what are the dimensions of the rectangle? which of the following equations could be used to solve the problem? 2x + 2(x - 3) = 54 2x + 2x - 3 = 54 2x - 3 = 54

The equation is 2(x-2)+2x=54.  This is because the perimeter of the rectangle is all of its sides added together and we know that the two sides that are opposite from each other are equal so if you know the longer side (x) and shorter side (y) you can just say the perimeter (p) is p=2x+2y.  
In the question we know that y=x-3 and p=54 so you can just write it as  54=2x+2(x-3)
I hope this helps.  Let me know in the comments if anything is unclear.

I believe the correct answer would be 2x+2(x-3)=54