Darius spent many days at the river last summer. He noticed that five out of every eight flying insects he saw at the river were mosquitoes. Enter a variable for the number of flying insects and use this variable to write an expression for the number of mosquitoes. If Darius saw eight flying insects at the river one day, how many were mosquitoes? If, over several days, Darius saw twenty four flying insects, how many were mosquitoes?