Q # 1:

during the first hour, the northbound train has travelled 63 miles.

during the 2nd hour, the north bound train has travelled another 63 miles while the southbound train which has just taken off at the start of the 2nd hour, has travelled 57 miles.

at 2 hours and 30 minutes, northbound train has travelled 31.5 miles, and the southbound train has travelled 28.5 miles.

add them up, and you’ll get 243 miles. therefore the answer is 2 hours and 30 minutes..

there is a formula for this but this is the best way i could explain it. drawing it will help you a lot.

as for the 2nd question, again there’s a formula for this which I dont remember at the moment. haha! im in med school now, so i forgot all about this already..

north left first…. so 63

plus 1 hour on both

63+63+57

then half hour for both

63+63+57+28.5+31.5=243

Total travel time is 2 and one half hours

2) I think it’s 1.5 kilograms

But not positive.