Question 494388
Distance(d) equals Rate(r) times Time(t) or d=rt; r=d/t and t=d/r

Now we know that the two cars are separating at the rate of 60+72=132kph
So, in 90 min (1.5hr) they are 132*(1.5)=198 km apart.

Another way:
In 1.5hr, car A travels 60*(1.5)=90km
In 1.5hr, car B travels 72*(1.5)=108km
90+108=198km


Hope this helps---ptaylor