Brian leaves Eagle Nest Campground at 830 am and hikes along

Brian leaves Eagle Nest Campground at 8:30 am, and hikes along a trail at 4kph. One hour later, Rob leaves the same campground and hikes along the same trail at 6 kph. At what time of day will he catch up with Brian?

Solution

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