I don't understand.

Question

If the constant of proportionality (C.O.P.) for a proportional relationship is 15 miles traveled per hour given, give the unit rate point for that graph and add any two additional points on the graph. 

Answer 1

y = kx

y = 15x

When x=1, y = 15 so I guess the "UNIT RATE POINT' is (1,15)

Other points can be calculated using other values of x.

Answer 2

The graph is a plot of distance (miles) vs. time (hours).  It is a straight line with a positive slope of 15 miles per hour, passing through (0,0) and (1,15).  The rate is the slope, which in this case is a speed, 15 miles/hour.  It is the same as the C.O.P.