Vector-related math questions

1. A boat sails directly north at 14m/s across a river which is 200m wide. The river flows from west to east at 2,5 m/s, whilst a south-easterly wind is blowing at 10m/s. Calculate the boat's resultant velocity and the time it would take to reach the opposite side.

2. The boat can sail 4m/s in still water and is aiming North whilst the river is flowing at 2,5m/s to the East. If a wind blows from the East at 1m/s, calculate the resultant velocity of the boat.

3. A motorcyclist travels north at 80km/h whilst an Easterly wind is blowing at 50km/h. Calculate the size and direction of the wind experienced by the motorcyclist.

4. A stationary soldier observes an enemy vehicle 1300m away which is moving at 25m/s at a right-angle upon the soldier's sight. If his mortar travels at 200m/s, how far in front of the vehicle must he aim to hit the vehicle?