If sixth term of a H.P. is 161 and its tenth term is 1105, then first term of that H.P. is
T6 of H.P. = 161⇒T6 of A.P. = 61
and T10 of H.P. = 1105⇒T10 of A.P. = 105,
so, a + 5d = 61 ........(i) and a + 9d = 105 .....(ii)
From (i) and (ii), a= 6
Therefore first term of H.P. = 1a = 16.