\( = \frac{{\frac{a}{2} - \frac{{3a}}{{16}} \times \frac{{3a}}{4}}}{{\frac{3}{4}}} = \frac{{\frac{{5a}}{{16}}}}{{\frac{3}{4}}} = \frac{{5a}}{{12}}\)
\(y = \frac{{M\frac{b}{2} - \frac{M}{4} \times \frac{{3b}}{4}}}{{M - \frac{M}{4}}} = \frac{{5b}}{{12}}\)