Question

the price per gallon of gasoline changes off the most drivers pay close attention to the changes find the percent changes in price for each of these cases increased from $4 per gallon to $4.20

Answer 1

since it went up .20 we are looking for the percentage .20 is out of 4. since .20 is 20% out of 1, divide 20 by 4 to find the new percent which is 5%. therefore the gas prices increased 5%, and the new price is 105% of the original price.

Answer 2

4 + 4x = 4.20
.2 = 4x
.2/4 = x
x = 1/20 = .05 = 5%