That Michael has a ratio of selling 1 flower every 2 hours.
Michael sold 2 flowers in 4 hours and 3 flowers in 6 hours and 4 flowers in 8 hours and 5 flowers in 10 hours, so If you count the pattern of the flowers she sold one each time he mentioned flowers and he sold it every 2 hours. So in that case, Michael has a ratio of selling 1 flower every 2 hours.