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%.

Richard earns $1000 a month. He received a raise of $91 per month. What is the percent of increase in his salary?

The percent of increase is %