Calculate how much gasoline and money could be saved if the automobile's fuel efficiency were increased by 25%.

gasoline = 25 gallons per week
money = $2 per gallon ($50 total)

In the question it is already given the amount of actual gasoline and money consumed before the fuel efficiency gets increased by 25%
Gasoline consumption before the increase in fuel efficiency = 25 gallons per week
Gasoline saved after the increase in fuel efficiency = [25 * (25/100)] gallons per week
                                                                                             = 6.25 gallons per week
So every week 6.25 gallons of gasoline can be saved after increasing the efficiency of the automobile by 25%.
Then
The amount of money saved against the 6.25 gallons of gasoline saved = (6.25 * 2) dollars
                                                                                                                   = 12.50 dollars
The amount of money saved is $12.50 per week.