(4,3) and (r,4) and a slope of 1/2

Question

Fine the value of r

Answer 1

1/2 = (4 - 3)/(r - 4)

Cross multiply

r - 4 = 2

r = 6

Answer 2

 

slope =  (change in y) / (change in x)    (another way to remember it:  "rise over run" )

 

slope = 1/2 = (3-4)/(4-r)

         

4-r = 2(3-4)

4-r = -2

-r = -6  

 

r = 6

-----------

 

I arbitrarily chose (r,4) as the "start" and (4,3) as the "end."   You should now take the time to prove to yourself that this  works even if you reverse the two points.