How do you calculate percent decrease?

To calculate percent decrease, the correct process involves taking the difference between the old value and the new value, then dividing that difference by the old value. The formula can be summarized as follows:

1. Subtract the new value from the old value to find the decrease.
2. Divide the decrease by the old value to determine what fraction of the old value the decrease represents.
3. Multiply the result by 100 to express it as a percentage.

This formula reflects how much less the new value is in comparison to the old value, providing a clear understanding of the reduction in terms of a percentage.

In contrast, the other options presented do not correctly reflect the process of calculating percent decrease. They either calculate an increase or use the wrong values and operations, leading to inaccurate results. Always remember that percent decrease specifically focuses on the original (old) value as the baseline for comparison.