This question is an example of d = r * t
r = rate
r = 3*10^8 m/s
t = ??
d = 7.5 * 10^6 meters.
Sub and solve
d = r * t
7.5 * 10^6 = 3 * 10^8 * t Divide both sides by 3 * 10^8
7.5 * 10^6 / (3 * 10^8) = t
2.5 * 10^(6 - 8) = t
2.5 * 10^-2 seconds = t or
0.025 seconds = t