I'm currently really lost for as how to do these:

For each, I need to find i) the resultant velocity, ii) distance travelled across the river and iii) time it takes to cross river

b) a boat moving at a velovity of 10km/h heads upstream. The river is flowing at a velocity of 6km/h in an Easterly direction. The river is 1.2 km wide. If the boat ends up directly across from where it started, find i) ii) and iii)

For i) I got 11.67 km/h but that isn't right :/

c) a boat moving at a velovity of 10km/h on a bearing of N20^{o}E, heads across a river which is flowing at a velocity of 6km/h in an Easterly direction. The distance across the river is 1.2 km. Find i) ii) and iii)

d) A boat moving at a velocity of 12km/h heads upstream at a bearing of N27^{o}W. The river is flowing at a velocity of 7 km/h in an Easterly direction. The riveri s 350m wide. Find i) ii) iii)

For this one, I tried to equate the i and j components and then find the magnitude of the resultant vector. That was wrong too :C

Any help would be reallyyyy appreciated, this is practice for a major test.