The institute of Electronics and Communications Engineers of the Philippines (IECEP) is planning to put up its own building. Two proposals being considered are:

A. The construction of the building now to cost P 400,000

B. The construction of a smaller building now to cost P300,000 and at the end of 5 years, an extension to be added to cost P 200,000.

By how much is proposal B more economical than proposal A if interest rate is 20% and depreciation to be neglected?