\[(x - 5)(x + \ *) = \ *\ - x - 20\]
\[x^{2} + x \cdot \ *\ - 5x - 5 \cdot \ *\ = \ *\ - x - 20\]
\[x^{2} + 4x - 5x - 5 \cdot 4 = x^{2} - x - 20\]
\[(x - 5)(x + 4) = x² - x - 20.\]