a) Pf=1800-10/100 * 1800
=1800-180=1620
b)Pf=5-20/100 *5=5-1=4
c)Pf=80+20/100*80=80+160=240
d)Pf=1200-10/100*1200=1200-120=1080
Pf=1080+20/100*1080=1080+216=1296
e)Pf=300+10/100*300=300+30=330
Pf=330+10/100*330=330+33=363
Pf=>pret final
Pi=>pret initial
r/100=>reducere si formula este Pf=Pi +sau - r/100*Pi daca este reducere este -daca este scumpire este +