1. **State the problem:** We are given the expression $a = 5 + x$ and need to understand or work with it. 2. **Explanation:** This is a simple algebraic expression where $a$ depends on $x$. The value of $a$ changes as $x$ changes. 3. **Formula:** The expression itself is the formula: $$a = 5 + x$$ 4. **Important rules:** - Addition is commutative: $5 + x = x + 5$ - You can substitute any value for $x$ to find $a$. 5. **Example:** If $x = 3$, then $$a = 5 + 3 = 8$$ 6. **Summary:** The expression $a = 5 + x$ defines a linear relationship between $a$ and $x$ where $a$ increases by 1 for every increase of 1 in $x$.