If a farmer can trade four chickens for a pig, three pigs for two sheep, and five sheep for two cows, what is the minimum number of cows he needs to trade for 20 chickens?
+37153 4ch/p x 3p/2s x 5s/2co
= 60 ch/4co
20ch/ (60ch/4co) = 80/60 cows 1 1/3 cow (~~ he will need two cows)
