Let T stand for Time [spent].
Let M stand for Money.
Let G stand for Girls.
Let E stand for Evil.
Girls take Time.
G = T
Time is Money.
T = M
Money is the root of all Evil.
M = E^(1/2)
If G = T, T = M, and M = E^(1/2), then
G = E^(1/2).
Therefore, Girls are the root of all Evil.