MPG"S 1996 v6

Hello, I have a 1996 chevy corsica, v6, 3.1 liter. Just replaced the fuel pump, and now the gas gauge doesn't work. Does anyone know approx. the average mpg, on this vehicle. New spark plugs and wires, no misses. Have done some reading but still a little confused. Thanks in advance fro any help. It is greatly appreciated.

mine gets between 25-30
but thats highway and town
it also depends how u drive it..haha