Of the following, which is the most appropriate linear model for the given data?

The correct answer is:

By observation we get few point (0, 7), (7, 0), (2, 5), (4, 3) and (6, 1)
Step 1:- Let ax + by = c be the appropriate linear model for data
Substitute (7, 0) in ax + by = c ⇒ c = 7a
Substitute (0, 7) in ax + by = c ⇒ c = 7b
We get c = 7a = 7b i.e b = a
Step 2:- Substitute b = a and c = 7a  in equation  ax + by = c
ax + ay = 7a ⇒ x + y = 7
So y = 7 - x is the Appropriate linear model for given data