Final answer:
The percent increase in the price of unleaded gasoline from 1990 to 2008 was approximately 193%.
Step-by-step explanation:
To find the percent increase, we need to calculate the difference between the two gas prices and then divide that difference by the original price. So, the difference is $4.02 - $1.37 = $2.65. Then, we divide $2.65 by $1.37 and multiply it by 100 to get the percent increase.
Percent increase = ($2.65 / $1.37) * 100 = 193.43%. Rounding to the nearest percent, the increase is approximately 193%.