if 600=3/4 then you divide both by 3 and you get 200=1/4 do fine unit rate multiply both sides by 4 and you get 800km/hr divide 800 by three to get one third of it (266 and 2/3) then multiply it by two (533 and 1/3) you must add the two thirds to the one to get 1333 and one third.