| first of all the speed of light isn't 3.0*105km/s, it's 3.0*10^5km/s so we'll use this value.
time taken = distance/speed so....
t = 2.3*10^8 / 3.0*10^6 seconds
t = 0.7666*10^3
t = 766.6 seconds
minutes = seconds/60 so
t=766.6/60 = 12.77minutes
sorry about your second question, i was never any good at algebra |