Question

The perimeter of a rectangle is 104m. Its lengthis 3 times its width .find its length and breadth

Answer 1

we are given that perimeter of rectangle is 104m and its lenght should be 3 times its width.

Let the width be x.

Let the length be 3x

Perimeter of rectangle = 2(L+B)

 104 = 2(3x + x)

104 = 2(4x)

104= 8x

104 ÷ 8= x

13 = x

The length of rectangle is 3x= 3 × 13= 39m

The breadth of rectangle is x= 13m

Answer 2

let length and breadth be x and y
2(l+b) is the formula
2(x+y)=104
x+y=52
let it be equation 1
according to the second sentence
x=3y
x-3y=0
equation 2
x+y=52
x-3y=0
- + - ( changing of symbols)
4y=52
y= 52/4
y=13
substitute y=13 in eq 1
x+13=52
x=52-13
=39