Question

Dupa doua reduceri consecutive de pret, prima de 5% iar a doua de 15% un frigider costa 646 lei.Care a fost pretuil initial al frigiderului?

Answer 1

x=pretul initial
x-(5%)x-(15%)((x-(5%)x)=x-(5x/100)-(15/100)((x-(5x/100))=
x-(x/20)-(3/20)((x-(x/20))=x-(x/20)-(3x/20)+(3x/40)=
x-(4x/20)+(3x/400)=x-(x/5)+(3x/400)=(4x/5)+(3x/400)=323x/400
Deci
(323x/400)=646
x/400=2
x=800