- Identify the equation: \(13 = m + 21\).
- Isolate the variable \(m\) by subtracting 21 from both sides: \(m = 13 - 21\).
- Calculate the final value: \(m = -8\).
- The final answer is \(\boxed{-8}\).
Explanation
- Analysis of the problem
The given equation is \(13 = m + 21\). The objective is to isolate the variable \(m\) to find its value. This is a linear equation in one variable, which we can solve by performing algebraic operations on both sides of the equation.
- Solving the equation for m
To isolate \(m\), we need to remove the constant term 21 from the right side of the equation. We do this by subtracting 21 from both sides of the equation:
\[13 - 21 = m + 21 - 21\]
Simplifying both sides, we get:
\[-8 = m\]
Thus, the value of \(m\) is \(-8\).
Examples
Imagine you have a bank balance of 13 dollars, but you just paid a bill of 21 dollars. To find your current balance, you can express your new balance \(m\) as \(m + 21 = 13\). Solving this equation tells you that your balance is \(-8\) dollars, indicating you have an overdraft of 8 dollars. Understanding how to isolate variables is crucial for managing finances and solving many real-world problems involving missing information.