Question

Pretul unui obiect creste cu 5% si dupa un timp sa micsoreaza cu 20% , pretul final este de 151,2.
MULTUMESC!!!

Answer 1

100%-20%=80%
151,2:80%=151,2:80/100=151,2×100/80=189 lei

100%+5%=105%
189:105%=189:105/100=189×100/105=180 lei  pret initial

Answer 2

Notam astfel
105/100 ·x=y
80/100 ·y=151,2(lei)
y=151,2/80/100
y=151,2·100/80=151,2·5/4
y=189(lei)
105/100·x=189(lei)
x=189/105/100
x=189·100/105=189·20/21
x=180(lei-pretul initial al obiectului);