Reacher. always draw a little `scratch` diagram to help give you the picture. Q3 Stop A as B leaves.A is now 140 nm down track, distance remaining 660 nm apart; now do it as in Q2.ie 660/360 =1.833 hrs; 120 x1.833=220 nm (from B); CHECK 1.833 X 240 =440NM, PLUS 140=580 nm( fromA) . Time ==00.35 plus 1.50 ( 1h 50 min =1.833x60)=02.25 hrs.Check-2h25m =145 min, x 4nm/min(for A) =580 nm
Takes a lot longer to write it than it takes to do either mentally or using a calculator. Always check you have a `sensible` answer.
All the best and keep practising...