The answer is 425 miles.
Both of the companies can be represented by an equation. The first company being f(a) and the second company bring f(b).
f(a)=$0.06x+65
f(b)=$0.10x+48
We want to find where they are equal, so we can set the equations equal to each other.
$0.06x+65=$0.10x+48
From here we can simplify the equation.
17=$0.04x
425=x
2 ,3,5,7,11,17,19,23,29,31, 37,41,43,47,53,59,61
67,71,73,79,83,89,97.....
The answer is B, 7.6-(-1.7)=9.3