Nothing to worry about, Emmanuel! This is easier than it looks, though you will need a calculator for the final step. Ready?
If you draw the journey south as a line, then turn east and drive a little less, you could follow that "straight line" trip back to the start as the hypothesis of the triangle. That means you use the Pythagorean Theorem:
A² + B² = c²
Since the hypotenuse is the only part you don't know, plug in the others, square, add, then take the root and get C.
See? You can do this easily!
