a firefighter is standing on the middle rung of a ladder.she moved up 9 rungs.the smoke got worse.so she moved back down 13 rungs when the smoke cleared she wentup 19 rungs to the top how many rungs does the ladder have

Question

jamesj · Answer

Let x be the number of rungs.  So she starts at x/2
then she goes to 
x/2 + 9
then to 
x/2 + 9 - 13
then to
x/2 + 9 - 13 + 19 --- (**)
and now she's at the top.  

What must this expression (**) be equal to?