If we know that A3 = 2, a7 = 1 in {an} and that {an} is an arithmetic sequence, then A8 =?

If we know that A3 = 2, a7 = 1 in {an} and that {an} is an arithmetic sequence, then A8 =?

A3 = a1 + n * 2 = 2, a7 = a1 + n * 6 = 1, the tolerance of {an} is n = - 1 / 4, then A8 = A7 + n = 3 / 4