Simple math.
Area = length * width
while
Perimeter = 2 (length + width) or P = 2L + 2W
So in order to find the length, we must compute first the width.
I will use the Perimeter.
So it will be like this,
90 = 2l + 2w
Divide both sides to two
45 = L + W
move length to left and change sign like this,
45 - L = W
therefore width is equal to 45 - length
We now use it to the Area.
Area is equal to 350 m^2
350 = L * (45 - L)
350 = 45L - L^2
move 45L - L^2 to the left and change sign
L^2 - 45L + 350 = 0
then factor
(L - 10) (L - 35)
therefore
L = 10 or 35
Since we are talking about rectangular, I suppose that 35 could be the length here and 10 will be the width.
I hope it helps.
