Volume and surface area question??

"The lateral edges of a regular hexagonal pyramid are all 20 cm long, and the base edges are all 16 cm long. To the nearest cc, whta is the volume of this pyramid? To the nearest square cm, what is the combined area of the base and six lateral faces?"

For the volume, I was very confused. I tried to take one third of the base and multiplied it by the height, but I don't know if that is only for regular pyramids. I got 3200 but I don't know if I'm right because I tried it again and I got a diff answer? I haven't done the surface area yet but I'm just so confused, could someone explain to me how this is done.