algebra
posted by snow .
2,200 after 3 years if the account pays 8.4%
i have no clue what this is

What is the question?
It helps to post the complete question even though there is more typing to do.
I suppose the question requires you to calculate the original deposit (principal) three years ago.
At 8.4% p.a. compound interest,
$1000 will yield 1000*(1.084³) after three years, or $1273.76.
If the combined interest and principal after three years is $2200, the the principal can be calculated by proportion, namely
P=1000*(2200/1273.76)=$1727.17
So check if my assumptions correspond to those of the question. If not, please post the complete question.