Answer:
It would take approximately 31.2×10^6 years
Step-by-step explanation:
Average speed = distance/time
Time = distance/average speed
distance = 8.1 light-years = 8.1×9.461×10^12km = 7.66341×10^13km
average speed = 280km/hr = 280km/hr × 8766hrs/year = 2454480km/year
Time = (7.66341×10^13km)/(2454480km/year) = 31.2×10^6 years