The square root of D.W.I.

A solution to the word problem, from our friend Xander:

H = X * Y + Z / U where U is an undefined variable
J = (Z-3) + U + (SqRt (X*Y))

HU = X * Y + Z
HU - Z = X * Y
Z = HU - (X * Y)

So

J = ((HU - XY)-3) + U + (SqRt (XY))
J-SqRt(XY) = (HU-XY)-3 + U
U = J-SqRt(XY) - (HU-XY) + 3

Therefore, we can easily deduce that after a mere 4 days you attempt to purchase a tranquilizer gun, but are arrested on the way home for:
Driving While Impaired (sleep deprivation, I am sure)
Carrying a Concealed Weapon
Possession of a firearm without a license

...

I think I understood the part about "driving while impaired."