If you illustrate the problem, you will somewhat come up with the figure shown. The missing value is the hypotenuse of the right triangle. Using the pythagorean theorems, the value is determined to be
x = √(0.7^2 + 2.4^2)
x = 2.5 km
2.5 km is the magnitude of the distance. If you want to incorporate the displacement, the answer is reported as 2.5 km, southeast. The direction is determined from the starting point to the endpoint.
