Percentages

x% = x/100, i.e., percentage of x means, per cent or per hundred, we have x.

If you take 30 matchsticks out of a box of 60 matchsticks, then according to unitary method, you are taking 1 matchstick out of every 2 matchsticks. Hence, out of 100 matchsticks, you take 50. Thus, you have taken 50% of the matchsticks.

Percentage is usually used to express percentage change in certain amount.

Percentage increase/decrease in a quantity
= [(change in quantity/original quantity)*100]%

If x is increased by a% and again it is reduced by b% to get back x, then a>b. 

If x is decreased by a% and then it is increased by b% to x, then a<b.

For successive increase or decrease of percentage, the order can be changed anyhow, i.e., x with a% increase, then b% increase followed by c% decrease and d% increase is equal to x with b% increase, then d% decrease, then c% decrease and finally a% increase.