The average monthly rainfall for the previous 9 months was 4 inches. Did the town exceed its average annual rainfall? If so how much? (the average annual rainfall of the town is 43.2 inches and the monthly average rainfall is 3.6 inches)

The town did exceed its average annual rainfall, it actually exceeded the annual rainfall by 3.6 inches.

you know this by dividing the rainfall of 43.2 by 3.6, which shows you that 43.2 is the rainfall over a 12 month period when we are looking at a 9 month period. Then you want to times 3.6 by 9 which gives you 32.4, after doing so times 4 times to find out the new rainfall and then subtract the new average by the old to find that it did exceed it.