(a) If \(17x = 375^{2} - 356^{2}\), find the exact value of x.

(b) If \(4^{x} = 2^{\frac{1}{2}} \times 8\), find x.

(c) The sum of the first 9 terms of an A.P is 72 and the sum of the next 4 terms is 71, find the A.P.