please solve the equation showing each step to get the points to find the slope.
-2x+4y=9
Pick any x you want and compute y.
Then do it again for a different x.
Connect the two points with a straight line, on a graph. Then measure the slope. That is the "get the points" method. You just compute any pair of points on the line.
There ia an easier way:
Convert your equation to y = mx = b form. The slope will be the value of m
4y = 2x = 9
y = (1/2) x + 9/4
m = 1/2