Basically if you want to work this out you need to use what's called the "balance method". I'm not sure if you've heard of it or not but it basically means whatever you do to one side of the equation, you do to the other.
Our current equation is T x 0.75 = D, T representing the time and D representing distance traveled in kilometres.
The worded equation stated that the satellite travels ¾ of a kilometre (0.75 km) for every tenth of a second. Therefore we need to figure out how many thenths of a second would be in a minute.
10 x 1/10 = 1
60 x 1 = 60
Therefore 600 x 1/10 = 60
Now we can take the "T" out of our equation and replace it with 600
It now looks like this: 600 x 0.75 = D
Now we have all the numbers we just need to use arithmetic to figure out the rest.
600 divided by 4 is 150. Three times that is 450
So there you go... the satellite would travel 450km in a minute. Hope my explanation was helpful :)