Use complete sentences to describe how measurements of position in two directions (vertical and horizontal) are sufficient enough to describe the position of an object on a flat surface.

Essentially, you can always tell a thing's position by 3 coordinates. We also say that our world is three-dimentional: it has three dimensions -that's why three coordinates are needed. If something is on a flat surface, you know its one coordinate (all points on the same surface have the same coordinate) so you only need two more (you can call them vertical and horizontal)

126 maybe. sorry