Given:
Mileage of car, m=20 miles/gallon
Driving distance per day=25 miles.
Driving 5 days per week,
d=25*5
d=125 miles
Cost of gar per gallon=$2.60
The objectiv is to find the cost of gas per week.
Since his car can run 20 miles per gallon.
Then the required gallon to complete 125 miles is,
[tex]\begin{gathered} x=\frac{Total\text{ distance}}{miles\text{ per gallon}} \\ x=\frac{125}{20} \\ x=6.25\text{ gallon} \end{gathered}[/tex]Thus the required gallon of gas is 6.25.
Let's take the total cost as C.
Then the required formula to find the total cost per week is,
[tex]\begin{gathered} C=\text{Cost of gas per gallon}\cdot\text{required gallon for a w}ek \\ C=2.60\cdot6.25 \\ C=16.25 \end{gathered}[/tex]Hence, the cost of the fuel for 5 days in a week is $16.25.