math
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?

Let R = rungs
.5R + 6  10 + 18 = R
Solve for R. 
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 ,answer clearly because I'm want to explain for my son how to solve the problem.Thanhs a lot. 
you are finding how many steps are from the middle to each end of the ladder so you have 2n. next you know the middle step is going to count as 1 so you have the equation 2n + 1
up 6 down 10 up 18
6  10 +18 =14
2n + 1
2 (14) + 1
28 + 1
29 steps 
11