Answer:
The first term is -3.
Step-by-step explanation:
Arithmetic sequence:
In an arithmetic sequence, the difference between two consecutive terms is always the same, and it is called common difference d.
The nth term is given by:

In which
is the first term.
If we have the mth term instead of the first, we have:

We have the third term, and need the fifth and the sixth:
So we write both the fifth and the sixth in function of the third, then:


The sum of the fifth and sixth term of an AP is 30
We use this to find
. So





First term:
The third term is:

Since 

The first term is -3.