You can
put this solution on YOUR website!Time going 300 miles at (255+x) = Time going 210 miles at (255-x).
Remember

means
so,

means that
76500 - 300x = 53550 + 210x
76500 -53550 - 300x = 53550 - 53550 + 210x
22950 - 300x = 210x
22950 = 510x
x=

= 45 mph.
I'm not sure what to put in the table!! Sorry.
R^2 at SCC