#### Answer

$y=7$

#### Work Step by Step

RECALL:
(1) The slope-intercept form of a line's equation is $y=mx+b$ where m = slope and b = y-intercept.
(2) The slope of a line can be found using the formula $m=\dfrac{y_2-y_1}{x_2-x_1}$ where $(x_1, y_1)$ and $(x_2, y_2)$ are points on the line.
(3) The slope of a horizontal line is $0$ and its equation is of the form $y=k$ where $k$ is the y-coordinate of any point on the line.
(4) The slope of a vertical line is undefined and its equation is of the form $x=h$ where $h$ is the x-coordinate of any point on the line.
Solve for the slope to obtain:
$m=\dfrac{7-7}{4-1}
\\m=\dfrac{0}{3}
\\m=0$
The slope is zero therefore the line is horizontal.
The y-coordinate of the point is $7$.
Thus, the equation of the line is $y=7$.