Knowledge of the pathology of spina bifida has helped:
more people prevent the disorder by getting enough vitamins.
more people receive surgery for the disorder
people with the disorder receive care for heart disorders
researchers study x linked disorders

According to an observer on earth, planet x is stationary. maria and samir depart earth on their spaceships at the same time, each flying at 0.5c. maria flies toward planet x and samir flies in the opposite direction. according to maria, her voyage to planet x takes 9 years. how many years does maria's voyage take according to samir?