Note that an is the next term following an-1
an+1 is the next term after an
The common difference is 0.4 - 1.2 = -0.8
And the first term is 1.2 = a1
Next term = Previous term - 0.8, an = 1.2
So....the answer that makes sense is
an = an-1 - 0.8, a1 = 1.2
[ Second answer ]
Does this make sense???
Yea it kind of makes sense but I am a little confused. I am gonna talk to my teacher to help me with these types of questions.