Question

1. decrease 320 cm by 15%
2. decrease 1800 by 5%
3. decrease 2500 by 90%
4. decrease 300 by 32%
5. decrease 20 oz by 25%

Explanation:

Step1: For "Decrease 320 cm by 15%"

First, find 15% of 320. The formula for percentage decrease is \( \text{New Value} = \text{Original Value} \times (1 - \frac{\text{Percentage}}{100}) \). So, 15% of 320 is \( 320 \times \frac{15}{100} = 48 \). Then subtract this from 320: \( 320 - 48 = 272 \).

Step2: For "Decrease 1800 by 5%"

Using the same formula, 5% of 1800 is \( 1800 \times \frac{5}{100} = 90 \). Subtract from 1800: \( 1800 - 90 = 1710 \).

Step3: For "Decrease 2500 by 90%"

90% of 2500 is \( 2500 \times \frac{90}{100} = 2250 \). Subtract: \( 2500 - 2250 = 250 \).

Step4: For "Decrease 300 by 32%"

32% of 300 is \( 300 \times \frac{32}{100} = 96 \). Subtract: \( 300 - 96 = 204 \).

Step5: For "Decrease 20 oz by 25%"

25% of 20 is \( 20 \times \frac{25}{100} = 5 \). Subtract: \( 20 - 5 = 15 \).

Answer:

1. 272 cm
2. 1710
3. 250
4. 204
5. 15 oz