Question 4438
at the time of both mee they would have travelled same distance and meet at same time.
let it be x
time  = distance / speed

time taken by Brian = x/ 4

time taken by Rob  = x/6
x/4 - x/6 = 1
3x/12 - 2x/12 = 1
x =12

to travel 12 miles it takes 3 hrs for Brian (12/4)

they will meet at 11.30 am