1. What is \( 15 \% \) of 300 ? 2. What percent of 72 is 36 ? 3. If \( 45 \% \) of a number is 28 , what is the number? 4. What is the percent increase from 50 to 60 ? 5. What is the percent decrease from 100 to 80 ?

Let's solve each of the problems step by step. 1. **What is \( 15 \% \) of 300?** To find \( 15 \% \) of 300, we can use the formula: \[ \text{Percentage} = \left( \frac{\text{Percent}}{100} \right) \times \text{Total} \] So, \[ 15\% \text{ of } 300 = \left( \frac{15}{100} \right) \times 300 = 0.15 \times 300 = 45 \] 2. **What percent of 72 is 36?** To find what percent 36 is of 72, we can use the formula: \[ \text{Percent} = \left( \frac{\text{Part}}{\text{Whole}} \right) \times 100 \] So, \[ \text{Percent} = \left( \frac{36}{72} \right) \times 100 = 0.5 \times 100 = 50\% \] 3. **If \( 45 \% \) of a number is 28, what is the number?** Let the number be \( x \). We can set up the equation: \[ 0.45x = 28 \] To find \( x \), divide both sides by \( 0.45 \): \[ x = \frac{28}{0.45} \approx 62.22 \] 4. **What is the percent increase from 50 to 60?** The percent increase can be calculated using the formula: \[ \text{Percent Increase} = \left( \frac{\text{New Value} - \text{Old Value}}{\text{Old Value}} \right) \times 100 \] So, \[ \text{Percent Increase} = \left( \frac{60 - 50}{50} \right) \times 100 = \left( \frac{10}{50} \right) \times 100 = 20\% \] 5. **What is the percent decrease from 100 to 80?** The percent decrease can be calculated using the formula: \[ \text{Percent Decrease} = \left( \frac{\text{Old Value} - \text{New Value}}{\text{Old Value}} \right) \times 100 \] So, \[ \text{Percent Decrease} = \left( \frac{100 - 80}{100} \right) \times 100 = \left( \frac{20}{100} \right) \times 100 = 20\% \] In summary: 1. \( 15\% \) of 300 is **45**. 2. \( 36 \) is \( 50\% \) of \( 72 \). 3. The number is approximately **62.22**. 4. The percent increase from \( 50 \) to \( 60 \) is **20%**. 5. The percent decrease from \( 100 \) to \( 80 \) is **20%**.