V = d/t
The speed of light is 3.0 x 10^8 m/s
The distance traveled is 149 x 10^9 m
Filling in the equation
3.0 x 10^8 = 149 x 10^9 / t
Multiply by t
3.0 x 10^8 x t = 149 x 10^9
Divide by the speed
t = 149 x 10^9 / 3.0 x 10^8
t = 496.67 s or roughly 500 s