math 4 grade
posted by Thanh .
A firefighter stood on the middle rungs of a ladder ,spraying water on a burning house. He then climbed up 6 rungs before the heat of the flames caused him to come down 10 rungs.After some minutes he was able to climb 18 rungs to the very top of ladder .How many rungs did the ladder have ?
Please, help me out this more clearly.Thank a lot.