Your first step is to write this expression in point-slope form, which is as follows:
y - y1 = m(x - x1)
y1 and x1 are where you put the x and y values of your coordinates. m is the slope.
Your expression would be written like this in point-slope form:
y - 1 = -4/5(x - 5)
To get to standard form (Ax + By = C), simply simplify the expression as follows.
Distribute the right side:
y - 1 = -4/5x + 4
Add one to both sides:
y = -4/5x + 5
Now you want to get x and y on both sides:
Add -4/5x:
4/5x + y = 5
To make this better, cancel the fractions by multiplying the equation by 5:
4x + 5y = 20
That is your final answer!
