X :
19. Mr. Thomas earned $54,500 in his first year of teaching. Each year after that,
he will receive $1,500 more than the previous year. How much money will Mr.
Thomas earn in his 47th year of teaching?

Use the slope formula to solve this.

m = y₂ - y₁ / x₂ - x₁
So since the points are (4, 1) and (7, -2) here's how you'd work it out:

Substitute the variables for the corresponding number.
m = -2 - 1 / 7 - 4
Solve the top and bottom.
m = -3 / 3
Now divide.
m = -1

So your answer is B.