If you decrease by a given percent and then increase by the same percent, will you be back where you started? how do you know

Lets pick a random number, like 50. Lets decrease and increase it by 50%. After the decrease, you will get 25, but when you increase it by 50%, it's only 37.5. No, because when you decrease it, you have a smaller base, so it increases less than it decreases. 50% of 100 is 50, but 50% of 50 is 25. You can see there is a significant difference.