$\text{Time} = \dfrac{\text{Distance}}{\text{Velocity}}$
$T = \dfrac{484,000,900 - 93,000,000}{7,500}$
$T = 52,133.45 ~ \text{hrs}$
$T = 52,133.45 ~ \text{hrs} \times \dfrac{1 ~ \text{day}}{24 ~ \text{hrs}} \times \dfrac{1 ~ \text{yr}}{365 ~ \text{days}}$
$T \cong 6 ~ \text{years}$ ← answer
