Question 11858
Time going 300 miles at (255+x) = Time going 210 miles at (255-x).

{{{Time=(Distance)/(Rate)}}}
{{{300/(255 +x) = 210/(255-x) }}}


Remember {{{a/b=c/d}}} means {{{ad=bc}}}


so,{{{300/(255 +x) = 210/(255-x) }}} means that {{{300(255-x) = 210(255+x)}}}


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

x= {{{22950/510}}} = 45 mph.


I'm not sure what to put in the table!!  Sorry.


R^2 at SCC