gas issue

for some reason i think my gas gauge is broken. and the reason why i think its broken is bc whenever i put about half a tank it flys down after like ten min of driving to a quarter tank and whenever it reaches the quarter tank it goes down regularly it makes me po whenever i see it just go down to the quarter tank. so any ideas on whats wrong and how i can fix it thanks
 
how can i fix the sender or gauge
The sender is in the gas tank. It is part of the contraption that holds the fuel pump. It's kinda like a float device. Perhaps something is wrong with it. Now I'm not sure if there is some other sender elsewhere but this is the one I'm familiar with. It probably is not the gauge judging by the symptoms but it's probably easier to check it just in case before you drop the tank.