The sequence 3, 5, 7, 9, ... is an arithmetic progression with: - First term \(a_1 = 3\) - Common difference \(d = 2\) General \(k^{th}\) term: \(a_k = 3 + (k-1) \cdot 2 = 2k + 1\) For the \((n-2)^{th}\) term, substitute \(k = n-2\): \(a_{n-2} = 2(n-2) + 1 = 2n - 4 + 1 = 2n - 3\) The expression is \(2n - 3\)