At a supermarket, a certain item has increased from 75 cents per pound to 81 cents per pound. What is the percent increase in the cost of the item?

There was an 8% increase in the cost of the item.

If the price of gas increases from $1.00 per gallon to $1.21 per gallon, what is the percent of increase?

The percent of increase is 21%.

Marlis has 200 cards in her baseball card collection. She sells 11 of the cards. What is the percent of decrease in the number of cards in the collection?

The percent of decrease is %