Step 1: Start with the fraction 90/20.

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

90 ÷ 20 = 4.5

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

4.5 × 100 = 450.0%

Final Answer: 90/20 as a percentage is 450.0%.