Answer:
y = 3
Explanation:
The slope-intercept form of an equation of a line:

m - slope
b - y-intercept
The formula of a slope:

We have two points A(4, 3) and B(-1, 3).
Substitute:

The slope m = 0, therefore it's a horizontal line.
The equation of a horizontal line:
where a is any real number
The line passes through points A and B, where ordinates are equal 3.
Therefore the equation is
