1. The problem asks how we know that $a$ and $b$ are the answers. 2. In algebra, $a$ and $b$ typically represent solutions to an equation or variables found by solving. 3. We verify $a$ and $b$ by substituting them back into the original equation to check if they satisfy it. 4. If both $a$ and $b$ make the equation true, they are confirmed as the correct answers. 5. This method ensures the solutions are valid and consistent with the problem's conditions.