Find the equation of the line connecting (0, 5) and (-2, 0).
As we go from the first point to the second, x decreases by 2 and y decreases by 5. Thus, the slope of this line is m = rise / run = -5/(-2), or 5/2.
Starting with the general equation of a line in slope-intercept form, y = mx + b, substitute the knowns as appropriate to determine the value of b:
y= mx + b => 5 = (5/2)(0) + b. Then b = 5, and the desired equation is
y = (5/2)x + 5.
Check this! If we subst. the coordinates of (-2,0) into this equation, is the equation true?
0 = (5/2)(-2) + 5
Yes. So, y = (5/2)x + 5 is the desired equation.