A linear equation in one variable has exactly one solution, unless it is inconsistent (has no solution) or has infinitely many solutions.

Here’s a breakdown:

1. One solution: Most linear equations, like $ax + b = 0$, have exactly one solution. In this case, you can solve for $x$ as $x = -\frac{b}{a}$, where $a \neq 0$.

2. No solution: If the equation simplifies to a contradiction, like $0x = 5$, it has no solution. This is because there's no value of $x$ that makes the equation true.

3. Infinitely many solutions: If the equation is something like $0x = 0$, it’s true for any value of $x$. In this case, the equation has infinitely many solutions.

So, typically, a linear equation in one variable has one solution, but it can also have none or infinitely many solutions depending on the specific case.

Do you need any examples or a more detailed explanation?

Here are some related questions:

1. What happens if the coefficient of $x$ is 0 in a linear equation?
2. How do you recognize when a linear equation has no solution?
3. What is the general form of a linear equation in one variable?
4. How can you solve a linear equation in one variable step by step?
5. What is the graphical representation of a linear equation with one variable?

Tip: Always check if the coefficient of $x$ is zero before solving; it can drastically change the number of solutions.