Step-by-step explanation:
this line goes through the points (0, -3) and (4, 0).
so, the y-axis intercept is at y = -3.
therefore, the equation has to end with "- 3".
the slope (the factor of x in the equation) is the y/x ratio of the changes of y and of x when going from one point to the other :
x changes by 4 positive units (from 0 to 4), and y changes by 3 positive units (from -3 to 0).
so, the slope is 3/4.
and so, the equation is
y = (3/4)x - 3
