Answer:
20m * 7m.
Explanation:
The area of the yellow rectangle = 14*10 = 140m^2 = the area of the brown one.
The perimeter of the brown one = 54 so
2L + 2W = 54
L + W = 27
and LW = 140
L = 140/W
140/W + W = 27
140 + W^2 = 27W
W^2 - 27W + 140 = 0
W = 20,7
and L = 140/W = 7,20
Length = 20, width = 7.