Answer:
Step-by-step explanation:
The explicit formula for an arithmetic sequence is
where n is the position of the number in the sequence, a1 is the first number in the sequence, and d is the common difference between the numbers.
If we are looking for the 91st term, our n = 91;
our a1 is 28, and
the common difference is -20. Putting all that together gives us the explicit formula for this sequence:
and
and
so