technically you could write 60km/1.5hr but I think you meant km/hr.
So your traveling 60km every 1.5hours but you only want to know how much every one hour. think of 1.5 as 150% of what you want (which is one) take 60 divide it into one hundred pieces (60/150) then multiply buy 100% of what you want (quotient of last problem * 100)
final equation looks like this (60/150) 100 = 40 km/ hr
Ps. *=multiply