Answer:
 Length = 25 cm 
Breadth = 10 cm 
Step-by-step explanation: 
 Let breadth of the room be 'x' 
 Let length of the room be '' 
 Perimeter ( P ) = 70 cm 
 Now, let's find the breadth of the room 'x ' 
 Perimeter of rectangle = 2(l+b)
 plug the values 
 70=2(2.5x+x)
 Collect the like terms 
 70=2x3.5x
 Calculate the product 
 
 70=7x
 
Swap the sides of the equation 
 
 7x=70
 
Divide both sides of the equation by 7 
 
 7x / 7= 70/7
 
Calculate 
 
 x=10cm
 
Breadth = 10 cm 
 
Now, Let's find the length of the room ' 2.5x ' 
 
Length of the room = 2.5x
 
 
Plug the value of X 
 
 2.5x10
 
Calculate the product 
 
 25cm
 
Thus , The length and breadth of the room is 25 cm and 10 cm respectively. 
 
Hope this helps.. 
 
Best regards!!