fluid mechanics

Hi my name is Andy and i was in your FE prep class for the spring semester. I am working for Marathon in Findlay and I have a question for you dealing with our fluids class. I left my fluids book and notes at my house in Toledo and this problem is bugging the heck out of me because they were so easy but i can't remember it all. Right now i have tank 40 feet high filled with gas and it's sg is .75. Can you tell me what the equation the equation is for finding the pressure at the bottom of the tank? I think it is something like (h*sg*62.4) but i am not sure.