The driver of a vehicle approaching an intersection on a highway controlled by a stop sign shall, immediately before entering such intersection, stop at a clearly marked stop line, or, in the absence of a stop line, stop before entering the crosswalk on the near side of the intersection, or, in the absence of a marked crosswalk, stop at the point nearest the intersecting roadway where the driver has a view of approaching traffic on the intersecting roadway. Before proceeding, he shall yield the right-of-way to the driver of any vehicle approaching on such other highway from either direction. Where a “Yield Right-of-Way” sign is posted, the driver of a vehicle approaching or entering such intersection shall slow down to a speed reasonable for the existing conditions, yield the right-of-way to the driver of another vehicle approaching or entering such intersection from another direction, and, if required for safety, shall stop at a clearly marked stop or yield line, or, in the absence of a stop or yield line, stop before entering the crosswalk on the near side of the intersecting roadway where the driver has a view of approaching traffic on the intersecting roadway, and shall yield the right-of-way to the driver of any vehicle approaching on such other highway from either direction.