Answer:

Explanation:
density of the solid box material = 
density of the liquid material = 
Given that
solid box floats with two thirds of its volume submerged in a liquid
let V be the volume of the box
then,

⇒
so, the ratio of densities of solid and and the liquid is 2/3
Velocity = displacement / time
First, Always make sure that your units for things are the same. In this question, we are given time in seconds and hours. So, we need to make them all use 1 unit.
I will do seconds.
To convert 80km/h to m/s, divide by 3.6.
22.2222…. m/s = displacement / 2.1s
Multiply by 2.1s on both sides
46.6666……m = displacement
You travelled 47 meters.
I think it's C. if we're talking about a rover.
But if it's a rocket that's computerized and automatic (synonym of unmanned)... Then it's B.