You can
put this solution on YOUR website!THE SLOPE OF A LINE THROUGH THESE POINTS IS
(15-10)/(6-4)
5/2=2.5 THEREFORE FOR EVERY 2.5 MILE (Y) IT TAKES 1 MINUTE.
SOLVING FOR THE Y INTERCEPT(b)
15=2.5*6+b
15=15+b
b=0
Y=2X/5

(graph 400x400 pixels, x from -20 to 20, y from -20 to 20, y = 2x/5).