Note: When the vehicles heading towards each other meet,

they would have spent SAME time on their journeys since they started at same time.

So that, ratio of their speeds = ratio of their distances

..|----------------|----------||----------|----------------|

.P...............................M............X................Q......................[ M: midpoint; X: meet]

Speed ratio: 80 : 68 = 20 : 17

Difference in distance = 20u - 17u = 3u ------> 2 x 24 km = 48 km

So that, ................................1u -------> 48 / 3 = 16 km

Distance between P and Q = (20 + 17) x 16 = **592** **km**

Check: 592/(80+68) = 4 h

In 4 h, car went 320 km and truck went 272, which is 24 from midpoint (592/2)

Cheerio!