Lorry start at 6.00am while car start 2 hour later.
So, Lorry already at 2h × 50 km/h = 100 km ahead.

Speed difference between car and lorry
= 90-50
= 40 km/h
It mean every 1 h car is 40km closer to lorry.

40km→ 1h
100km → 100÷40 = 2.5 h
a) Car over take lorry at 8.00am + 2.5h (2h 30min)
= 10.30 am.

b) Total time taken by car
=2.5 + 2
= 4.5h
Distance
= 4.5 × 90
= 405 km