To find the percentage change from 300 to 90, we need to first calculate the difference between the two numbers.

Step 1: Difference = Final Value - Initial Value

Difference = 90 - 300

Difference = -210

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 = |-210|

Absolute Difference = 210

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

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

Percentage Change = (210 / 300) x 100

Percentage Change = 70%

Therefore, the percentage change from 300 to 90 is -70%. This means that there was a decrease of 70% from 300 to 90.