(1,25-1/2):75/2009*5/2009
(1,25-1/2):75/2009*5/2009= (1,25-0,5):75/2009*5/2009= 0,75*2009/75*5/2009= 3/4*1/75*5= 1/4*1/25*5= 1/4*1/5=1/20