`a_3 = 94, a_6 = 85` Find a formula for a_n for the arithmetic sequence.

We have to find the first term `a_1` and the common difference `d,` then the general formula will be  `a_n=a_1+(n-1)d.`

The difference between `a_6` and `a_3` is equal to 3 common differences, i.e.

`d=(a_6-a_3)/3=(85-94)/3=-9/3=-3.`

The first term is 2 common differences less than 3-rd, so

`a_1=a_3-2d=94+2*3=100.`

So the answer is: `a_n=100-(n-1)*3.`