subtract 3x from both sides of the equation to get:
4y = -16 - 3x
divide both sides of the eqution by 4 to get:
y = -16/4 - 3/4 * x
order the equation in descending order of degree and simplify to get:
y = -3/4 * x - 4
it has a slope of -3/4 and a y-intercept of -4.
the x-intercept is the value of y when the value of x is 0.
start with y = -3/4 * x - 4
set y = 0 to get 0 = -3/4 * x - 4
add 4 to both sides of the equation to get:
4 = -3/4 * x
divide both sides of the eqution by -3/4 to get:
4 / (-3/4) = x
solve for x to get:
x = -5.33333.....
here's a graph of the original equation, using the desmos.com calculator.
you can see that the y-intercept is x = -4
that's the value of y when the value of x is zero.
you can see that the x-intercept is y = -5.333.
that's the value of x when the value of y is zero, rounded to 3 decimal places.
you can see that the slope is -3/4 because, looking from left to right, you have the coordinate point of (-5.33333....., 0) and the coordinate point of (0,-4) on the line.
the slope is (y2-y1) / (x2-x1) = (-4 - 0) / (0 + 5.33333.....) = (-4 - 0) / 5.33333.....
this is equal to -4 / (16/3) which is equal to -3/4.