Answer:
111.
Step-by-step explanation:
The terms in an Arithmetic sequence are a1, a1 + d, a1 + 2d..... where a1 is the first term and d is the common difference,
Therefore for this sequence the common difference is (a27 - a1) / 26
= (66 - (-12) / 26
= 78/26
= 3.
The nth term an = a1 + (n - 1)d, so
the 42nd term a42 = -12 + (42-1)*3
= -12 + 123
= 111.
