Equations

Equation 1
Human = Eat + Sleep + Work + Enjoy .......(1)
Donkey = Eat + Sleep ........(2)
Therefore,
Human = Donkey + Work + Enjoy ........from (1) & (2)
Therefore,
Human - Enjoy = Donkey + Work
In other words,
Human that don't enjoy = Donkey

Equation 2
Man = Eat + Sleep + Earn Money ........(3)
From (2)
Donkey = Eat + Sleep
Therefore,
Man = Donkey + Earn Money
Therefore,
Man - Earn Money = Donkey
In other words,
Man that doesn't earn money = Donkey

Equation 3
Woman = Eat + Sleep + Spend .......(4)
From (2)
Donkey = Eat + Sleep
Therefore,
Woman = Donkey + Spend
Therefore,
Woman - Spend = Donkey
In other words,
Woman that doesn't spend = Donkey

Conclusion
From Equation 2 & Equation 3
Man that doesn't earn money = Woman that doesn't spend
So, men earn money not to let woman become a donkey! (Postulate 1)
And, women spend not to let man become a donkey! (Postulate 2)
So ultimately we have,
Man + Woman = Donkey + Earn Money + Donkey + Spend Money
Thus, the conclusion is,
Man + Woman = 2 Donkeys that live happily together!