Represent the unknowns.
Let x = length
since the width is 3/4 of the length,
Let (3/4)x = width
Recall that the area of rectangle is just width multiplied by the length,
A = w l
Substituting,
432 = (3/4)x x
432 = (3/4)x^2
432 * 4/3 = x^2
576 = x^2
Get the square root of both sides,
x = 24 feet (length)
