There is a ship which moves at 45 m/m with a load and moves at 60 m/m without a load under no flow of the water.
This ship goes back and forth the river whose speed of a flow is 15 m/m.
(1) One day this ship carried the load from A point to downstream B point.
When the load was taken down at B point and it moved to downstream C point further, it took a total of 2 hours.
It is 7.8 km from A point to C point.
Find the distance from A point to B point.
The time concerning taking down a load is not considered.
(2) On the other day, although the load has been dropped into the river as this ship is carrying the load toward downstream E point from D point, it moved as it is without noticing.
However, it noticed that it dropped before arriving at E point, it changed the direction and it went to the upper stream.
The load which has flowed from the dropped point were picked up, the ship changed the direction again and went to E point.
As a result, it took time 12 minutes more to carry the load than the schedule.
Find the time until the ship noticed dropping after dropping the load.
Time to change direction of the ship and time to pick up loads are not considered.