It would be $947.50 because you would multiply $189.50 by 0.05.
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


To find out how much is needed for 1 you will need to divide each given value by 4:
12 marshmallows / 4 = 3
8 graham crackers / 4 = 2
4 smores / 4 = 1
you then need to multiply each value by 3 :
3 marshmallows x 3 = 9
2 graham crackers x 3 = 6
1 smore x 3 = 3
therefore the answer would be :
9 marshmallows
6 graham crackers
hope this helps you