The distance between town X and Town Y is equal to the difference between the distance between Town X and Town Z and the distance from Town Y and Town Z. Mathematically
d (X-Y) = d (X-Z) - d(Y-Z)
Substituting,
d(X-Y) = 57 miles - 28 miles = 29 miles
Thus, the distance from Town X to Town Y is 29 miles.
The answer here is C. Let's proof.
Since we are dealing with whole numbers, select a constant for x to satisfy that y will result a whole number.
If x = 1, then the function would be 1 + 4y = 9. Solving for y,
4y = 9 - 1
4y = 8
y = 2
In ordered pair, that is (1,2)
Next, if x = 5, then 5 + 4y = 9. Solving for y,
4y = 9 - 5
4y = 4
y = 1
In ordered pair, that is (5,1).
Lastly, if x = 9, then 9 + 4y = 9. Solving for y,
4y = 9 - 9
y = 0/4
y = 0
In order pair, that is (9,0).
