If the mathematical operator `+` means `'xx','+'` means `'-','xx'` means `+` and `-` means `div` , then `25 + 18-3xx7 div 3 = ?`
A.25
B.21
C. 19
D. 40.

Options

A. B
B. A
C. D
D. C

Answer

To solve the expression \( 25 + 18 - 3 \times 7 \div 3 \) with the given operator transformations, we will first replace each operator according to the rules provided:

1. **Operator Transformations**:
- `+` means `-`
- `-` means `div`
- `xx` means `+`
- `div` means `*`

Now, let's rewrite the expression step by step:

### Step 1: Replace the operators
The original expression is:
\[ 25 + 18 - 3 \times 7 \div 3 \]

Replacing the operators:
- \( + \) becomes \( - \)
- \( - \) becomes \( \div \)
- \( \times \) (which is represented as `xx`) becomes \( + \)
- \( \div \) becomes \( \times \)

So, the expression becomes:
\[ 25 - 18 \div 3 + 7 \times 3 \]

### Step 2: Evaluate the expression
Now, we will evaluate the expression step by step:

1. **Evaluate \( 18 \div 3 \)**:
\[ 18 \div 3 = 6 \]

2. **Substitute back into the expression**:
\[ 25 - 6 + 7 \times 3 \]

3. **Evaluate \( 7 \times 3 \)**:
\[ 7 \times 3 = 21 \]

4. **Substitute back into the expression**:
\[ 25 - 6 + 21 \]

5. **Now perform the operations from left to right**:
- First, calculate \( 25 - 6 \):
\[ 25 - 6 = 19 \]

- Then, add \( 21 \):
\[ 19 + 21 = 40 \]

### Final Answer
Thus, the final result of the expression \( 25 + 18 - 3 \times 7 \div 3 \) with the transformed operators is:
\[ \boxed{40} \]