From the 3rd term to the 8th term, we'd need to use the "common difference" or "d", 5 times, namely add it that many times, to get the 8th term, thus
we know the 3rd term is -12, so the first one has to be -12+5+5, undoing the -5's, so the first term is -2.
we know the 3rd term is -12, so the first one has to be -12+5+5, undoing the -5's, so the first term is -2.
