1. The problem statement, all variables and given/known data Two moons orbit a planet in nearly circular orbits. Moon A has orbital radius r, and moon B has orbital radius 5r. Moon A takes 50 days to complete one orbit. How long does it take moon B to complete and orbit? 2. Relevant equations Kepler's Third Law 3. The attempt at a solution I know we're supposed to attempt it, but I'm not even sure I'm heading in the right direction! Can anybody give me some insight?