If a quantity increases by 25% and then decreases by 25%, will the resultb e the original quatity?

No the result will not be the original quantity, it will be less than the original.

Example: 100 increased by 25% becomes 125. 125 decreased by 25% becomes 93.75. This holds true for any number.

This is because you are taking 25% of the marked up number and not the original number.

You actually won't get the same answer Becuz when you increase 25% to a number. and the decrease 25% from that number you won't get the original amount. since your not decreases. 25 from the original number