The taxi fare after each km, when the fare

No, because the total fare (in ?) after each km is

15,(15+ 8), (15 + 2 x 8), (15+ 3 x 8),…= 15,23, 31, 39,…

Let $\quad t_{1}=15, t_{2}=23, t_{3}=31$ and $t_{4}=39$

Now, $t_{2}-t_{1}=23-15=8$

$t_{3}-t_{2}=31-23=8$

$t_{4}-t_{3}=39-31=8$

Since, all the successive terms of the given list have same difference i.e., common difference = 8

Hence, the total fare after each km form an AP.