Rachel has $1,800 to spend on renting a venue for a party. The available locations to rent for the party cost between $660 and $2,500. This cost includes a base cost, plus a set-up fee that is one-fifteenth of the base cost. The total cost can be modeled by the function shown below, where c represents the base cost of renting a venue. f(c)=c+1/5c
State the domain of values that represents the base cost for the venues Rachel can afford.