Divide each term in the polynomial by the monomial.

$\displaystyle\frac{{{5}{{a}}^{{6}}}}{{{20}{{a}}^{{4}}}}+\frac{{{60}{{a}}^{{5}}}}{{{20}{{a}}^{{4}}}}-\frac{{{40}{{a}}^{{4}}}}{{{20}{{a}}^{{4}}}}=\frac{{1}}{{4}}\cdot{{a}}^{{{6}-{4}}}+{3}\cdot{{a}}^{{{5}-{4}}}-{2}\cdot{{a}}^{{{4}-{4}}}=\frac{{{{a}}^{{2}}}}{{4}}+{3}{a}-{2}\usepackage{cmbright}\Huge\$