Aphelion is the point in the orbit of a planet at which it is furthest from the sun. Perihelion is the point
in the orbit of a planet at which it is closest to the sun. At aphelion, Pluto is approximately 49 AU from the
sun. At perihelion, Pluto is approximately 29.5 AU from the sun. In kilometers, how much farther is Pluto
from the sun at aphelion than at perihelion?