If i am paying 385 per month plus electric, cable and internet how much should i rent my extra bedroom out for?

i am thinking about renting my guest room out but i am un sure about what to charge if my rent is 385 per month my elec runs around 150 and my internet and cable is 107 what should i charge ? i want to be fair but i want to make money also . This is a college town here in greenville and the neighborhood is nice and convenient to stores, public trans and etc