Problem 20-3 Determine the centroid of the shaded area shown in Fig. P-705, which is bounded by the \(x\)-axis, the line \(x = a\) and the parabola \(y^2=kx\)

\(A = \frac{2}{3}ab\), \(\bar{x} = \frac{3}{5}a\), \(\bar{y} = \frac{3}{8}b\)