Question

Pretul unui obiect dupa o majorare de 10 % respectiv o reducere de 20 % ajunge sa fie 2640.Aflati pretul initial.

Answer 1

x- pret initial
x+10x/100=A unde A reprezinta noul pret dupa marire
A-20A/100=2640  aducem la acelasi numitor

100A-20A=264000
80A=264000
A=3300

x+10x/100=3300  amplificam cu 100
100x+10x=330000
110x=330000
x=3000

Answer 2

100+10/100 ·p=n ,100-20/100 ·n=2640[lei]
⇒110/100 ·p=n ,80/100 ·n=2640[lei]
⇒80/100 ·n=2640[lei]
⇒n=2640/80/100
⇒n=2640·100/80
⇒n=2640·10/8
⇒n=2640·5/4
⇒n=660·5⇒n=3300[lei]
⇒110/100 ·p=3300[lei]
⇒p=3300/110/100
⇒p=3300·100/110
⇒p=3300·10/11
⇒p=300·10⇒p=3000[lei-pretul initial];