Step 1: Start with the fraction 45/12.

Step 2: To convert a fraction into a percentage, divide the numerator by the denominator.

45 ÷ 12 = 3.75

Step 3: Multiply the result by 100 to get the percentage.

3.75 × 100 = 375.0%

Final Answer: 45/12 as a percentage is 375.0%.