#### Answer

The cost for the rental would be:
$$$125 + $0.15x$$

#### Work Step by Step

We know that before we drive any miles, we already have to pay $125$ dollars for the week to rent the car, so we have to add $125$ to the mileage charge.
The mileage charge would be calculated by multiplying $0.15$ by the number of miles, $x$.
Putting it all together, we get:
$$$125 + $0.15x$$