Maddermatics

Some people tried too hard to work at mathematics and discovered some new formulae:-

ROMANCE MATHEMATICS
Smart man + smart woman = romance
Smart man + dumb woman = affair
Dumb man + smart woman = marriage
Dumb man + dumb woman = pregnancy

OFFICE ARITHMETIC
Smart boss + smart employee = profit
Smart boss + dumb employee = production
Dumb boss + smart employee = promotion
Dumb boss + dumb employee = overtime

SHOPPING MATH
A man will pay $2 for a $1 item he needs.
A woman will pay $1 for a $2 item that she doesn't need.

My comment for the last line: As in a sale, a woman will pay $2 for the $2 item that she doesn't need, if the price halved.