Check the forward differences of the sequence.
If
, then let
be the sequence of first-order differences of
. That is, for n ≥ 1,

so that
.
Let
be the sequence of differences of
,

and we see that this is a constant sequence,
. In other words,
is an arithmetic sequence with common difference between terms of 2. That is,

and we can solve for
in terms of
:



and so on down to

We solve for
in the same way.

Then



and so on down to


So what you do is theres 12 months so multiple that by 15 and get 180 then what you do is what time 80 equals 180 and thats your answer
22,200
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Answer:
45
Step-by-step explanation:
15% of 100 = 15
15 x 3 = 45