Length of the rectangle is 150 m.
Step-by-step explanation:
Step 1:
Let the width of the rectangle be x. Then the length = 3x. Given that perimeter = 400 m, find the length.
Perimeter of the rectangle = 2 (length + breadth)
400 = 2 (3x + x)
400 = 8x
∴ x = 400/8 = 50
⇒ Width is 50 m
∴ Length = 3x = 150 m