The lenght of a rectangle is 3 inches more then its width. Its perimeter is 42 inches, find the dimensions of the rectangle

The problem uses the perimeter formula.  P = 2w + 2l   where w is the width, and l is the length.

We know the length (l) is 3 inches longer than it's width (or l = w+3).  Substitute w +3 into Perimeter equation.

P = 2w + 2(w+3).  That simplifies to P = 4w + 6.

Since P + 42,   we have 42 = 4w +6.  With some simple algebra we find that w = 9 and l = 12.

it would rotate about 180 degrees.