When was the sunrise that day?

Question

One person A start with constant speed at sunrise at A-town and move towards B-town. Another person B starts also with constant speed at sunrise at B-town and move towards A-town. They met at noon (12.00) but continue with no stop. A arrived at 4pm to B-town and B at 9pm to A-town. When was the sunrise that day.

Answer 1

they meet at C at noon

A arrives at B, going a distance BC in 4 hours

B arrives at A, going a distance AC in 9 hours

Using A and B for the persons is a little confusing as it's also used for the locations.

But person A goes 60 mph starting at 6am sunrise, riding 10 hours, going 600 miles from A to B

Person B goes 40 mph starting at 6am sunrise riding 15 hours going 600 miles from B to A

Let t= time before noon, the time from start to meeting

Let x = person A's speed and y = person B's speed. distance = speed times time

distance AB = x(4+t) =y(9+t)

4x+9y = yt+xt

4x-9y = yt- xt add to eliminate y

8x = 2yt

4x = yt

y = 4x/t

x(4+t) = 9(4x/t) +4x= x(36/t+4)

4+t = 36/t + 4

t = 36/t

t^2 =36

t = 6 hours before noon was sunrise