When \(\mathrm{e}^{5 y}\) is plotted against \(x^{3}\), a straight line passing through the points \((-2.56,4.38)\) and \((6.54,9.84)\) is obtained. (a) Find \(y\) in terms of \(x\).

(b) Find the values of \(x\) for which \(y\) can exist.