The 5th of n arithmetic sequence is 5 less than the 20th term of an arithmetic and the 7th term is 12,find a and d and first 3 terms.
The 5th of n arithmetic sequence is 5 less than the 20th term
d = 5/15 = 1/3
the 7th term is 12
a+6d = 12
so a = 10
so the sequence is
10, 10 1/3, 10 2/3, 11, ...