Answer: a) k=8
b) The area of the addition =
The area of the entire patio after addition 
Step-by-step explanation:
Given: The area of the patio before addition = 50 square feet
The area of the addition portion is given by 
We can see that dimension of the total portion is 
therefore, the area of the patio with the addition portion = 
According to the question we have,

Therefore, The area of the addition =
The area of the entire patio after addition = 