Question 1049669
slower train speed r

time   7

distance 7r


fast train speed r+150
time 2

distance (r+150)*(2)


at t=7 distance are equal
(r+150)(2)=7r
2r+300=7r
r={{{60}}} mph
faster train speed is {{{210}}}

check
first train leaves at 2,
after one hour 60 miles
after 2 hour 120
after 3 hour 180
after 4 hour 240
after 5 hour 300 
after 6 hour 360
after 7 hour  420 miles this is 9pm
second train leaves at 7
after one hour 210 miles
after 2 hour 420 miles    this is 9 pm
after 3 hour 630 miles