Help with Center of M Physics Problem?

A future space traveller is in an escape capsule, far from any significant sources of gravity. To fix his emergency beacon, he climbs the entire length of a ladder, in the positive direction, that runs from one end of the capsule to the other. As he climbs, the capsule undergoes a displacement of −16.0 m. If the capsule has a m of 5.00×103 kg and the space traveller has a m of 95.0 kg, what is the length of the capsule? ume that the capsule's center of m is halfway between its ends.