Answer:
$26
Explanation:
To find your answer, simply plug in Francesca's time and Phil's time to your cost equation.
Francesca can be represented by the following equation:

Phil can be represented by the following equation:

As such, Francesca pays $13 and Phil pays $39. Next, since you want to find how much more Phil paid, all you have to do is subtract 13 from 39. That will give you $26.