Question 919073
t = D/r
times  the same
Bev = Susan's time
{{{600mi/(r+10) = 500mi/r}}}
600r = 500r + 5000
100r = 5000
r = 50mph, Sue's speed.  Bev's is 60mph {{{50+10}}}
And...checking
600/60 = 500/50 = 10hr