The perimeter of a rectangular painting is 5103m2 . If the length of the painting is 63m , what is its width?
I think that you must mean that the AREA = 5103 m^2 [ perimeter is a linear measure ]
So
Area = W * L
5103 = W * 63 divide both sides by 63
81 (m) = W
Is this the same person who posted the question below this? It is the same answer, it is 81.
If not, Look at cpill's answer
Perimeter doesn't have a square... but I'll solve it!
5103-63(2) will be length^2, so just square root the answer!