This is the concept of trigonometry;
Using the Pythagorean theorem, the elevation of the starting point will be given by:
c^2=a^2+b^2
c^2=7^2-3^2
c^2=49-9
c^2=40
thus;
c=6.325 km
therefore the starting point of the camp was:
6.325-0.6
=5.725 km
The answer is 5.725