150nm at original ground speed (240kts) would take 37.5 minutes.  

Aircraft has covered 150nm in 39.5 minutes = ground speed 228kts.  

Remaining distance to run is 480 – 150 = 330nm and at revised ground speed of 228kts this will take 86.8 minutes.  

Total elapsed time = 39.5 + 86.8 = 126.3 minutes (2h06m).  

Departure time is 1000 add elapsed time 2h06m, ETA = 1206.