Answer:
5 meters
Explanation:
First Rectangle :
Let the width = x
Given that length of the garden is 3 times that of width
Length = 3x
Second Rectangle:
As the width of both the rectangle is same
Width = x
Also given that the length of second rectangle is 3 meters more than that of first rectangle
Length = 3x+3 = 3(x+1)
Also given that Area = 90
Area = length * width

Hence either
x-5=0 or x=5
or
x+6=0 making x=-6 which is not possible as width can not be negative
Hence the width of the gardens is 5 meters