If that is the question there is a rather lengthy list of accompanying questions. Will the adult guppies get fed any other food? Is there any one else in the tank? Are the adult guppies of mixed gender?
Four adult guppies of mixed gender in a tank that are fed at least once daily and have no other occupants will become 4000 guppies in about 4 months. If they adults eat the fry, they don't eat enough of them to make any difference in the size of the population.