An island is overtaken with bunnies. However, there isn't enough food for them all and the population starts to decline. At year one, there are 1,000 bunnies roaming around. At year two, there are only 500 bunnies. At year
three, there are only 250 bunnies left roaming around.

Write an explicit equation to represent the number of bunnies (B) after a number of years (t)