Here, a = –11, d = –7 – (–11) = 4, an = 49
We have an = a + (n – 1) d
So, 49 = –11 + (n – 1) × 4
i.e., 60 = (n – 1) × 4
i.e., n = 16
As n is an even number, there will be two middle terms which are 16/2th and (16/2 + 1)th, i.e., the 8th term and the 9th term.
a8 = a + 7d = –11 + 7 × 4 = 17
a9 = a + 8d = –11 + 8 × 4 = 21
So, the values of the two middle most terms are 17 and 21, respectively.