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%.

Mr. Havel bought a car for $2100 and sold it for $2184. What was the percent of profit for Mr. Havel in selling the car?

The percent of profit was %