Question

write the length and breadth if the ratio is 7:5and perimeter is 240

Answer 1

Given ratio of a rectangle = 7:5
Let the length be 7x 
Breadth be 5x
Then perimeter = 2(l+b)
                         = 2(7x +5x)
But given that the perimeter = 240
⇒ 2(7x+5x) =240
⇒ 2(12x) = 240
⇒  12x = 240/2
⇒  12x = 120
⇒    x =120/12
∴ x = 10
The length = 7x =7(10) = 70 units
The breadth = 5x = 5(10) =50units

Answer 2

2(l+b)= perimeter
2 (7x + 5x) = 240
( 12x ) = 240/2
x = 120/12
x = 10

length = l = 7x = = 7(10) = 70 
breadth = b = 5x = 5 (10) = 50

lenght is 70 and breadth is 50.