The three percentage questions
What is 15% of 200? Multiply: 200 × 0.15 = 30. Used for tips, taxes, and discounts.
30 is what percent of 120? Divide and multiply: 30 ÷ 120 × 100 = 25%. Used for scores, shares and proportions.
Change from 80 to 100? (100 − 80) ÷ 80 × 100 = +25%. Used for growth, price changes and statistics — note the change is always relative to the starting value.