2/10=1/5, so all odd numbers are out leaveing you with the choose of 4 slices and 6 slices i do not know wich is right becase you did not give the amount of apple pie they ate. if they ate 2 slices or 2/5 of the apple pie then they ate 4 slices of the blueberry pie, if they ate 3 slices or 3/5 of the apple pie then they ate 6 slices of the blueberry pie. i hope i helped and sorry for spelling. im better at math than english