a) Cost of 18 miles trip = 249.
So cost of 1 mile trip = 249/18 = $ 13.8333333
But after rounding it to one decimal place the answer becomes $13.8
b) For $249 you can travel 18 miles.
So for $1 you can travel 18/249 = 0.07 miles
After rounding the solution becomes 0.1 miles.