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15 decreased by 20% = 12

15 decreased by 20 percent is 12. Step-by-step solution with the formula and worked example.

15 decreased by 20% = 12
decreased by %

Solution: 15 decreased by 20 percent

Decrease = 20% × 15 = 3
Result = 15 − 3 = 12

Step-by-step explanation

  1. Find the decrease: 20% of 15 = 3.
  2. Subtract it from the original: 15 − 3 = 12.
  3. Shortcut: multiply by (1 − 20/100) = ×0.8.

Good to know

Shortcut: decreasing by 20% is the same as multiplying by 0.8 (that is 100% − 20%). So 15 × 0.8 = 12 in one step.

Frequently asked questions

15 decreased by 20 percent
15 decreased by 20% = 12.

How is it calculated?
See the step-by-step solution above — it uses the standard percentage formula.

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