Equation 1

Human = eat + sleep + work + enjoy
Donkey = eat + sleep
=> Human = Donkey + work + enjoy
=> Human – enjoy = Donkey + work

In other words, Human that don’t know enjoy = Donkey that work
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Equation 2

Men = eat + sleep + earn money
Donkeys = eat + sleep
=> Men = Donkeys + earn money
=> Men – earn money = Donkeys

In other words, Men that don’t earn money = Donkeys
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Equation 3

Women = eat + sleep + spend
Donkeys = eat + sleep
=> Women = Donkeys + spend
=> Women – spend = Donkeys

In other words, Women that don’t spend = Donkeys
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To Conclude:

From Equation 2 and Equation 3
Men that don’t earn money = Women that don’t spend.
So, Men earn money not to let women become Donkeys! (Postulate 1)
And, Women spend not to let men become Donkeys! (Postulate 2)

So, we have? Men + Women = Donkeys + earn money + Donkeys + spend money
Therefore from Postulates 1 and 2, we can conclude
Man + Woman = 2 Donkeys that live happily together!