Question 130923
let speed of car=C , speed of train=T (in mph)
given that C=2T
from A to B is 300miles=482803.2meter
speed of car= distance traveled(meter)/time(hour)
            = 482803.2/7.5
            = 64373.76mph

from C=2T, T=C/2
            =64373.2/2
            =32186.88mph

the speed of car and train travel from A to B are 64373.76mph and 32186.88mph