Răspuns :
p=pretul initial al produsului, p-10p/100=p-p/10=9p/10=pretul dupa ieftinire
9p/10+(9p/10)x10/100=396, 9p/10+9p/100=396, numitor comun 100
90p+9p=39600, 99p=39600, p=39600/99=400 lei
9p/10+(9p/10)x10/100=396, 9p/10+9p/100=396, numitor comun 100
90p+9p=39600, 99p=39600, p=39600/99=400 lei