Answer:
y = (4/3)x - 3
Explanation:
I'll assume the question is to determine the equation of a straight line that passes through points (3,1) and (0,-3).
Let's look for an equation in slope-intercept form of y = mx + b, where m is the slope and b is the y-intercept.
Slope is the Rise/Run of a line
Rise is the change in the y axis, As x goes from 3 to 0 (a change of -3), the value of y goes from 1 to -4, a rise of (1 - (-3)) = 4.
I personally like to order the points from lowest to highest x, moving to the right. We can more easily envision that the line is headed up, from -3 to 1, as x goes from 0 to 3.
============
See the attached worksheet.
In both cases, the Rise/Run (the slope, m) is (4/3).
We can now write:
y = (4/3)x + b
To find b, we can use either of the two points and solve for b. Lets use point (3,1).
y = (4/3)x + b
1 = (4/3)(3) + b
b = -3
The equation is therefore:
y = (4/3)x - 3