A geostationary satellite in orbit around the earth has a period identical to that of the earth's daily rotation; the radius of such an orbit is 4.23 \times 10^4 kilometers. A system of satellites is proposed such that 15 satellites are in orbit at the same radius and each passes over a point fixed on the Earth 14 times per day (the times will be evenly spaced). What will be the orbital radius of each satellite? There will be two such radii; only the smaller will be practical. I wish I knew where to begin...help please!