To find the percentage, you divide the new price ($39.90) by the original price ($38), and the multiply it by 100 to change the answer from a decimal to a percentage:
39.90 / 38 x 100 = 105
So 39.90 is 105% of 38
To get our final answer, subtract this by 100%
105 - 100 = 5%
ANSWER: So the percentage increase of the price is 5% ($1.90)