You have 1/4 of a tank of gas and 10 dollars in your wallet. gas is $2.50/gallon and your car holds 13 gallons. explain how you would find out how many total gallons you will have in your car after you put in $10 worth of gas.

Best way to start this is to figure out how much gas you can get for that $10.  Since gas is $2.50/gallon and you buy $10 worth, that says you'll get 4 gallons of gas ($2.50 * 4 = $10).  Now figure out how many gallons you have left in your car.  If you car holds 13 gallons, 1/4 of that is 3.25 gallons.  Add the 3.25 gallons left to the 4 gallons you bought and you get 7.25 gallons in your car.