<h2>Answer with explanation:</h2>
Let x denotes the number of days and y denotes the total change in gas price ( in dollars).
Given : During the past seven days the price of regular gas is decreased by $0.2 each day.
Rate of decrease =$0.2 per day
Then , Total change in gas price = Rate of decrease x Number of days
i.e.
i.e. (1)
To find the total change in gas price in 7 days , we put x= 7 in (1) , we get
Hence, the total change in gas price in 7 days = $1.4