1. The problem asks to decrease 80 by 15%. This means we want to find 15% less than 80. 2. The formula to decrease a number by a percentage is: $$\text{New value} = \text{Original value} \times (1 - \frac{\text{percentage}}{100})$$ 3. Here, the original value is 80 and the percentage decrease is 15%, so substitute these values: $$\text{New value} = 80 \times (1 - \frac{15}{100})$$ 4. Simplify the fraction: $$\text{New value} = 80 \times (1 - 0.15)$$ 5. Calculate inside the parentheses: $$\text{New value} = 80 \times 0.85$$ 6. Multiply to find the new value: $$\text{New value} = 68$$ So, the new value after decreasing 80 by 15% is **68**.