Respuesta :

18 divided by 3 is 6, giving us what 1/4 of the journey is. 6 times 4 gives us 4/4 or 1 whole race, therefore the race is 24km long. 
Piinoy
Just divide the size by cost, and see which one was the lowest.

10 / .79 = ~12.66
15 / 1.29 = ~11.63
18 / 2.16 = ~8.33
32 / 3.19 = ~10.03

18 ounces had thw lowest unit price.