Final answer:
To calculate the percentage increase in gas price, find the difference between the new and old prices, then divide it by the old price. In this case, the price of gas increased by 20%.
Step-by-step explanation:
To calculate the percentage increase in gas price, we need to find the difference between the new and old prices and then divide it by the old price.
The price increase can be calculated as follows:
Price increase = New price - Old price = $1.50 - $1.25 = $0.25
Percentage increase = (Price increase / Old price) * 100% = ($0.25 / $1.25) * 100% = 20%
Therefore, the price of gas increased by 20%.