Girls are Evil
Proof: Girls are the root of all evil.
If girls require time _and_ money, should that be stated: Girls = Time + Money
This leaves us with, using the well-known fact that time is money: Girls = 2*Money
Under the assumption that money is the root of all evil, it can now be found that: Girls = 2*sqrt(evil)
In words, girls are _twice_ the root of all evil, instead of just evil