Question 914338
C for cost, d for distance
p, a constant of proportionality for DIRECT VARIATION


{{{C=pd}}}


Let C = 84 Php
Let d = 320 km


{{{p=C/d}}}
{{{p=84/320}}}
{{{highlight(p=0.2625)}}}   Php per km, the PRICE for each kilometer...


I made a couple small adjustments to your whole description plus question, but something is wrong with one, the other, or the two of them. Is Php 84 the price or the cost of the trip?  Cost and price are not the same thing.