Answer:

Where y is the total amount earned, m the amount for each extended warranty and b the fixed cost and x the total amount of TVs
For this case the value of x = 16 since we have 16 Tvs with extended warranties and we can do this:

and solving for b we got:

And then we can conclude that she earns 60 for each TV
Step-by-step explanation:
For this case we can set a linear model like this:

Where y is the total amount earned, m the amount for each extended warranty and b the fixed cost and x the total amount of TVs
For this case the value of x = 16 since we have 16 Tvs with extended warranties and we can do this:

and solving for b we got:

And then we can conclude that she earns 60 for each TV
Let

. Then

. By convention, every non-zero integer

divides 0, so

.
Suppose this relation holds for

, i.e.

. We then hope to show it must also hold for

.
You have

We assumed that

, and it's clear that

because

is a multiple of 3. This means the remainder upon divides

must be 0, and therefore the relation holds for

. This proves the statement.
The answer is A. Those are the four points that are graphed.