I willl assume that the width is three fourths of the length: W = (3/4)L. Then
the perimeter is P = 252 cm = 2(W) + 2L = 2(3/4)L + 2L, in terms of L only.
Then (6/4)L + 2L = 252 cm. Clear out the fraction by mult. all terms by 4:
6L + 8L = 252 cm, or 14L = 252 cm. Solving for L, L = 252 cm / 14 = 18
The length, L, is 18, and the width, W, is (3/4)(18 cm) = 13.5 cm (answer)
