This kind of question is a "number is what percent of number" problem. To solve this, divide the first number (22.5) by the second number (90) and multiply by 100. 22.5 / 90 = 0.25 0.25 • 100 = 25 So 22.5 is 25% of 90.
You can check this by doing 0.25, or just 25%, times 90. 0.25 • 90 = 22.5 This clarifies that 25% is the correct answer.