Answer
$\text{slope}=m=-\frac{1}{2};
\\\text{y-intercept}=b=2$
Refer to the image below for the graph.
Work Step by Step
RECALL:
The slope-intercept form of a line's equation is:
$y=mx+b$
where $m$ = slope and $b$ = y-intercept
Write the given equation in slope-intercept form by isolating $y$ on one side to obtain:
$x+2y=4
\\2y = -x+4
\\y=\frac{-x+4}{2}
\\y = -\frac{1}{2}x+2$
The equation above has:
$\text{slope}=m=-\frac{1}{2};
\\\text{y-intercept}=b=2$
To graph the line, perform the following steps:
(1) Plot the y-intercept point $(0, 2)$.
(2) Use the slope $-\frac{1}{2}$ to find another point on the line.
From $(0, 2)$, move down 1 unit (the rise) and move 2 units to the right (the run) to arrive at the point $(2, 1)$.
(3) Complete the graph by connecting the two points using a straight line.
(refer to the attached image in the answer part above for the graph)