x-pretul initial
majorarea: x+15x/100=(100x+15x)/100=115x/100=23x/20
ieftinirea: 23x/20-(23x/20)·15/100=23x/20-69x/400=(460x-69x)/400=391x/400
391x/400=195,5
x=(195,5·400)/391
x=200 lei pretul initial al pantofilor
b) pretul dupa majorare: 200+200x15/100=200+30=230 lei