If she can wash 15 dishes in 5 minutes you just need to figure out how many dished she can washe in 1 minute. so you are gonna divide 15 by 5 and get 3 because 3 times 5 equals 15. so then that means she can wash 3 plates in 1 minute. so if she washed 15 in 5 in 6 minutes she can wash 18 and in 7 minutes she can wash 21 and in 8 minutes she can wash 24. Your just adding 3 to the 15 for every minute.
