Benjamina has walked two legs of a right triangle, so you can connect her two movements with a line if you were sketching the situation.. The displacement is the objects overall change in position in relation to its origin, so in your case, Benjamina's apartment. While the total distance adds up regardless of her position.
So, the total distance Benjamina walked is 10m + 6m = 16m
Her displacement can be found by your best friends, the Pythagorean Theorem: 10m ^2 + 6m ^2 = delta x^2 (or displacement squared).. giving you a displacement of 11.66, or 12 m
The difference between the distance she walked and her displacement is 4 meters.
