To find the percentage change from 80 to 64, we need to first calculate the difference between the two numbers.

Step 1: Difference = Final Value - Initial Value

Difference = 64 - 80

Difference = -16

Step 2: Next, we need to find the absolute value of the difference. This is because percentage change is always calculated as a positive value.

Absolute Difference = |Difference|

Absolute Difference = |-16|

Absolute Difference = 16

Step 3: Now, we can calculate the percentage change using the formula:

Percentage Change = (Absolute Difference / Initial Value) x 100

Percentage Change = (16 / 80) x 100

Percentage Change = 20%

Therefore, the percentage change from 80 to 64 is -20%. This means that there was a decrease of 20% from 80 to 64.