For this case we must solve the following system of equations:

To solve we follow the steps below:
We multiply the second equation by -3:

Thus, we have the equivalent system:

We add the equations:

We look for the value of the variable "y":

Thus, the solution of the system is given by:

Answer:

Solution,
We have,
Width of rectangle, b = (2.5u+9.8) cm
Length of rectangle, l = (1.5u+3.9) cm
We need to find the expression for the perimeter of the rectangle. The formula for the perimeter of a rectangle is given by:
Perimeter = 2(l+b)
P = 2[(2.5u+9.8)+(1.5u+3.9)]
Collecting like terms
P = 2[(2.5u+1.5u)+(9.8+3.9)]
P=2(4u+13.7)
⇒ P = 8u+27.4
So, the expression for the perimeter of the rectangle is (8u+27.4) cm.
Answer:
exact form: 13 over 6
decimal form: 2.16
mixed number form: 2/ 1 over 6
14.5, 14.8, 15, 15.3, 15.8 Hope this helped!
-TTL