Question

The length of rectangle is twice its width If its perimeter is 54 cm find its length

Answer 1

Let the width of the rectangle be 'b'
Then the length be 2b
Given perimeter = 54 cm
2(l+b)=54
2(2b+b)=54
2(3b)=54
6b=54
b=9cm
Therefore length of the rectangle 2b=2(9)=18cm

Answer 2

Let the width be x
Length = 2x
Given perimeter = 54 cm
⇒ 2(2x+x) = 54
⇒ 2(3x) = 54
⇒ 6x = 54
⇒ x = 54/6
∴ x = 9
Width = x = 9cm
Length = 2x = 2(9) = 18cm