EV = C + I + O + Ex - Im
--> effective demand = consumtion + investments + government spending + export - import

EV=Y

Simple multiplier = deltaY/deltaAutonomous

1/[1-consumption(1-taxes)-import] --> marginal

Yes, they are letters and formulas.

Yes, they have to do something with Economics (we think).

Yes, the last formula is wrong.

Yes, tomorrow is my mid-term.

Yes, by accident you are the Nobel Prize Winner for Economics.

Yes, you will explain to me everything about the macro- and micro-economy.

Spank you very much !