Your question is a little bit unclear but I'll try to help:
When quantity increases, we can calculate it's percent increase using equation.
PERCENT INCREASE= (new amount−original amount)/original amount}
You can also multiply it by 100% go tet percent value.
When quantity decreases, you can calculate it's percent increase using equation.
PERCENT DECREASE=(original amount−new amount)/original amount
You can also multiply it by 100% go tet percent value.
