HELP. I need to understand this for a test tomorrow. THANKS

Consider planet mass of 4.98 E 21 kilograms with a satellite orbitting it at distance of 3.11 E 6 meters from planet's center. Satellite has mass of 369 kilograms.

How long (inseconds) does it take the satellite to make one complete orbit around planet.

I just can't seem to get the correct answer - Please show me step by step.

Thanks