My gas bill is $249.
That amount is 99% greater than the average of select, similar neighbors.
How do I get the value that would represent my bill absent the 99%?

I tried:
249 * -1.99 <-- doesn't work
x = 249 - .99 <-- looking at it, it doesn't make sense

?

(edit) I may not have provided sufficient information. The all neighbors average 226 Therms gas. I'm using 449 Therms. Given this information, could I just do a proportion 226/449 249/x?

Mark