Hint: If something is 1.275 times the original value then what do you need to multiply by to get 1.00? (Hint 1/1.275).
Another way of thinking about it: If X is the original amount and it has been "inflated by 27.5%", it has been increased by .275X so is equal to X+ .275X= 1.275X= 336. Divide both sides by 1.275.
(That is mathematics. It has nothing to do with "Excel".)