Don't be afraid of formulas. You just put something in, and something pops out.
n is the number of the term
For example, to get the first term, n is 1
To get the second term n is 2
1st term A1=3-5*(1-1) = 3-5*0 = 3
2nd term A2 = 3-5*(2-1) = 3-5*(1) = -2
3rd term A3= 3-5*(3-1) = 3-5*2 = -7
The small number on A shows what number term.
To get the common difference subtract any term by the term before it.
For example, subtract the 3rd term by the 2nd term. OR subtract the 5th term by the 4th term.
It's called a common difference because the subtraction answer you get is the same, no matter which term you choose.
3rd term - 2nd term =
-7 - (-2) = -5