Answer:
-89
Step-by-step explanation:
The first term of the sequence is a1 = -12.
The common difference between terms is ...
d = -13 -(-12) = -1
The generic term is given by ...
an = a1 +d(n -1)
Then the 78th term is ...
a78 = -12 +(-1)(78 -1) = -12 -77
a78 = -89
