for most graphing software, you need to solve for y.
take x + 4y = 20 and subtract x from both sides and then divide both sides by 4 to get 4y = 20 - x which becomes y = (20 - x) / 4
for slope and y-intercept information, you would would want to convert to slope intercept form of y = mx + b, where m is the slope and b is the y-intercept.
additionally, you may wish to find the x-intercept.
the desmos.com software will allow you to graph any of these forms.
to convert to slope intercept form, you are basically solving for y and then ordering the terms in descending order of degree.
for example, you already solved for y to get y = (20 - x) / 4.
simplify this to get y = 20/4 - x/4 which can further be simplified to y = 54 - x/4.
you then arrange the terms in descending order of degree to get y = -x/4 + 5.
all 3 forms are shown on the graph.
you can see that they all draw the same figure on the graph.
that's because they're all equivalent to each other.
the slope of this equation is -1/4.
the y-intercept is the value of y when x is equal to 0 which is equal to 5.
the x-intercept is the value of x when y is equal to 0 which is equal to 20.