Okay, so you know that . You also know that q= c- dp.
So
Notice that the two "cd" and "dc" terms cancel, leaving cb- da= bc- ad. Of course, because it is subtracted, becomes .
I'm working from a book called Mathematics for Economics and Finance (Martin Anthony and Norman Biggs) I have a problem with one of their damn examples on supply and demand.
the supply set is S={(p,q)|q=bp-a} and D={(p,q)|q=c-dp}
when an excise tax is imposed i need to find the equilibrium quantity ( )
this is found by finding the equilibrium price ( )
So I solve simultaneously and get:
which is in the book. Now I need to find qT which the book states is found by:
I can't figure out how the hell these people managed to get bc-ad, Can someone tell me how they got this!?