Imagine you are living in the 1400s and, as most people did then, you live off of the land. You raise cows, sheep, goats, etc., to provide food and clothing. Limited money exchange is available, most commonly in the form of silver and gold coins, though you most often barter for goods using what you could raise, grow, or build.
Think of some kind of common activity you might be planning or you might need to do in the course of your daily living. It might have to do with increasing the size of your fields, adding space to your house, fencing around your animals, how milk production would change if you bought another cow, how much cloth you could make from the wool from your sheep, how you might barter with your neighbor or at the marketplace, etc.
How would you express these ideas, which are quantifiable, in words?
Remember, it is 1400. Everything is in words-no symbols. For instance, I might say "The wool from three sheep is equal in value to the milk produced in three days' time from two cows." Or, "If I make each side of my fence twice as long, the grazing area for my animals would be..."