Find the 20th term of the AP whose 7th term is 24 less than the 11th term, first term being 12.
Let the a be first term and d be common difference
As we know
an = a + (n - 1)d
Given,
a7 = a11 - 24
a + 6d = a + 10d - 24
10d - 6d = 24
4d = 24
d = 6
given a = 12
then, a20 = a + 19d
a20 = 12 + 19(6)
= 12 + 114
= 126