Luis put $800 in his saving account whichs pays 6% annual interest How much will he have in his account in a year if the interest is compounded quarterly?

what is the first quarter principle?

There are four periods, each (a quarter) will be paid (1/4) of 6% interest.

The accumulated amount at the end of the year will therefore be
A = 800*(1+0.06/4)^4
=$849.09