Custom operation evaluation: Given a * b = a + b + a / b, find the value of 12 * 4.

Introduction / Context:
This problem defines a custom binary operation and asks for a direct evaluation. The key is to substitute exactly as defined and respect standard arithmetic precedence (division before addition).

Given Data / Assumptions:

• Definition: a * b = a + b + a / b
• Compute: 12 * 4

Concept / Approach:
Plug in a = 12 and b = 4 directly into the given definition. Do not overthink; there is no associativity or commutativity assumption needed for a single operation.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

• 48: Treats * as multiplication; incorrect by definition.
• 20/21: Often arise from adding in a different order or misreading the division.

Common Pitfalls:

• Assuming standard multiplication instead of the defined operation.
• Forgetting to perform a/b with correct precedence.

Final Answer: