Factor $LaTeX: \displaystyle 20 x^{3} - 25 x^{2} - 36 x + 45$ .

Grouping the first two terms and factoring out their GCF, $LaTeX: \displaystyle 5 x^{2}$ , gives $LaTeX: \displaystyle 5 x^{2}(4 x - 5)$ . Grouping the last two terms and factoring out their GCF, $LaTeX: \displaystyle -9$ , gives $LaTeX: \displaystyle -9(4 x - 5)$ . The polynomial now has a common binomial factor of $LaTeX: \displaystyle 4 x - 5$ . This gives $LaTeX: \displaystyle 5 x^{2} \left(4 x - 5\right) -9 \cdot \left(4 x - 5\right) = \left(4 x - 5\right) \left(5 x^{2} - 9\right)$ .