Solve the equation `a-15=25` and state which axiom do you use here.

Answer

To solve the equation \( a - 15 = 25 \), we will follow these steps:

### Step 1: Write down the equation
We start with the equation:
\[ a - 15 = 25 \]

### Step 2: Add 15 to both sides
To isolate \( a \), we will add 15 to both sides of the equation. This is based on the axiom that states if you add the same quantity to both sides of an equation, the equality is maintained.

\[ a - 15 + 15 = 25 + 15 \]

### Step 3: Simplify both sides
Now, we simplify both sides of the equation:
\[ a = 40 \]

### Conclusion
Thus, the solution to the equation \( a - 15 = 25 \) is:
\[ a = 40 \]

### Axiom Used
The axiom used in this solution is the **Axiom of Addition**, which states that if equal quantities are added to equal quantities, the results are equal.

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