\( - 2 b + 3 a c - 5 a b - 20 a - 1 \)

Let’s break down this expression. This is a polynomial in variables \(a\), \(b\), and \(c\). To simplify it, you can group like terms together. For instance, you have terms with \(a\) and terms with \(b\) that can be combined or factored if needed. This polynomial could potentially represent various scenarios in fields like physics or economics where variables interact in complex ways. Now, if you're trying to factor or solve this expression, remember to look for common factors first. For instance, if you're focusing on the term \( -5ab \) and \( -20a \), factoring out \(-5a\) gives you \(-5a(b + 4)\). It’s easy to miss common factors if you rush, so take your time and examine each term carefully!