She will be 55 meter far from the beginning of the track.
Step-by-step explanation:
Juliet starts at the 10-meter mark.
Initial displacement from starting = 10 meter.
She runs 45 meters to the 100 meter line.
Displacement = 45 meters.
Final displacement from starting = Initial displacement from starting + 45
Final displacement from starting = 10 + 45
Final displacement from starting = 55
She will be 55 meter far from the beginning of the track.