1. The problem is to understand what happened to the term $28x$ in an expression or equation. 2. Often, terms like $28x$ can be combined, factored out, or canceled depending on the context. 3. For example, if you have an expression like $28x - 28x$, these terms cancel each other out because $28x - 28x = 0$. 4. If $28x$ is part of a larger expression, it might be combined with like terms, e.g., $28x + 12x = (28 + 12)x = 40x$. 5. Without the exact expression, the most common reasons $28x$ might disappear are cancellation, factoring, or simplification. 6. If you provide the full expression or equation, I can show exactly what happened to $28x$.